Oxygen concentrator

Abstract

A handheld portable oxygen concentrator device is disclosed. The apparatus may include first and second columns, a product buffer, a plurality of valves fluidly coupling the first column, the second column, one or more pumps, and the product buffer. The apparatus may include a controller configured to repeatedly cycle the following stages: (a) raising pressure in the first column by connecting the first column to a positive pressure pump, and releasing concentrated oxygen in the first column to the product buffer, (b) equalizing the pressure in the first and second columns by connecting the first column to the second column, (c) reducing the pressure in the first column by connecting the first column to a negative pressure pump, and (d) equalizing the pressure in the first and second columns by connecting the first column to the second column.

Description

[0001] This application claims priority to U.S. Provisional Application No. 63 / 581,102, filed September 7, 2023, pursuant to 35 USC § 119(e), the contents of which are incorporated herein by reference in their entirety. Technical Field

[0002] The disclosed systems and methods relate to gas concentrators. Specifically, the disclosed systems and methods relate to handheld and portable oxygen concentrators using a pressure swing absorption process. Background Technology

[0003] Oxygen (O2) supplementation is an important therapeutic intervention used to manage a variety of medical conditions, including chronic obstructive pulmonary disease (COPD), heart disease, emphysema, fibrotic lung disease, pulmonary hypertension, cluster headaches, migraines, and asthma. It is also used in veterinary medicine to support animals with respiratory and cardiac conditions, and during surgery and recovery. Additionally, oxygen supplementation plays a role in wound care, accelerating healing and improving the health and appearance of the external epidermis. It is also commonly used in recreational settings, including to alleviate symptoms associated with altitude sickness and to enhance physical performance. Due to its widespread use, non-stationary oxygen supplementation is necessary in hospitals, homes, outdoor settings, and portable environments.

[0004] Oxygen replenishment is typically delivered via high-pressure cylinders, liquid oxygen, or medical oxygen concentrators (also known as stationary oxygen concentrators). Portable oxygen concentrators are portable versions of medical oxygen concentrators and offer numerous advantages that make them increasingly popular over cylinders or liquid oxygen. Summary of the Invention

[0005] The disclosed systems and methods relate to a portable oxygen concentrator. In some embodiments, the portable oxygen concentrator may be a handheld device. In some embodiments, the portable oxygen concentrator may include a first column and a second column, one or more pumps; a controller; a buffer; a reservoir; and a plurality of valves fluidly connected to the first column, the second column, and one or more pumps. In some embodiments, the first and second columns may contain an adsorbent. In some embodiments, the controller may be configured to: a) increase the pressure in the first column by connecting the first column to a positive pressure pump and release concentrated oxygen from the first column to a product buffer; b) equalize the pressure in the first and second columns by connecting the first column to the second column; c) decrease the pressure in the first column by connecting the first column to a negative pressure pump; and d) equalize the pressure in the first and second columns by connecting the first column to the second column.

[0006] In some embodiments, a portable oxygen concentrator may include a first column and a second column, the first and second columns containing adsorbent. The portable oxygen concentrator may also include one or more pumps, a plurality of valves fluidly connected to the first column, the second column, and the one or more pumps, and a removable module. The removable module may include a product buffer filled with adsorbent, an inflatable oxygen reservoir, and a duckbill valve having an opening pressure configured to inflate the inflatable oxygen reservoir.

[0007] It should be understood that the foregoing general description and the following detailed description are exemplary and illustrative only, and do not limit the claimed disclosure of embodiments. Attached Figure Description

[0008] The accompanying drawings are not necessarily drawn to scale or in detail. Instead, the emphasis is generally placed on illustrating the principles of the embodiments described herein. The drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. In the drawings:

[0009] Figure 1 A schematic diagram of an exemplary oxygen concentrator according to some embodiments of the present disclosure is depicted.

[0010] Figure 2 Describing for Figure 1 A schematic diagram of the cycle sequence and steps of an exemplary oxygen concentrator.

[0011] Figure 3A and Figure 3B Exemplary flowcharts for phase one and phase three of an exemplary oxygen concentrator according to an alternative embodiment of the present disclosure are depicted, respectively.

[0012] Figure 4 Depicting Figure 3A and Figure 3B Another exemplary flowchart of phases two and four of an exemplary oxygen concentrator.

[0013] Figure 5A A flowchart is depicted for a removable module of an exemplary oxygen concentrator according to some embodiments of the present disclosure.

[0014] Figure 5B , Figure 5C and Figure 5D Depicting the use of spherical materials as Figure 5A Three exemplary configurations of an oxygen storage unit within a removable module of an exemplary oxygen concentrator.

[0015] Figure 5E A diagram depicting the removable module is shown, highlighting the components used for measurement. Figure 5AThe first and second measurement points of oxygen product flow rate in the exemplary oxygen concentrator depicted in the figure.

[0016] Figure 6 Depicting in Figure 5E An exemplary output flow rate of an oxygen product measured at the first point of the removable module.

[0017] Figure 7 Depicting in various situations Figure 5E An exemplary oxygen product output measured at the second point of the removable module.

[0018] Figure 8A An exemplary setup using a dual-head pump as two separate pumps for pressure and vacuum is depicted.

[0019] Figure 8B An exemplary setup is depicted using a dual-head pump as a single pump to provide pressure or vacuum at any given time.

[0020] Figure 9A and Figure 9B A cross-sectional view of an exemplary U-shaped column of an exemplary oxygen concentrator according to an embodiment of the present disclosure is depicted.

[0021] Figure 10A A column-top filter element incorporating a filter assembly is depicted according to an embodiment of the present disclosure and can be used in an exemplary oxygen concentrator.

[0022] Figure 10B The wall height difference between the top filter element and the bottom filter element in an exemplary oxygen concentrator that can be used in this disclosure is depicted.

[0023] Figure 10C and Figure 10D A cross-sectional view of a spring installed between the bottom cover and the bottom filter element according to an embodiment of the present disclosure is depicted.

[0024] Figure 11 An exemplary flowchart depicts an exemplary automation process of an exemplary oxygen concentrator according to an embodiment of the present disclosure.

[0025] Figure 12 The pressure pump characteristic curve (f) of the pressure pump according to the embodiment of this disclosure is depicted. P ).

[0026] Figure 13 Vacuum pump characteristic curves (f) illustrating the vacuum pump characteristics according to embodiments of the present disclosure are shown. V ).

[0027] Figure 14 The correlations (f) with water pollution according to embodiments of this disclosure are depicted.m ).

[0028] Figure 15 Examples of embodiments of V according to this disclosure are illustrated. CLM The correlation (f) of the impact on product purity CLM ).

[0029] Figure 16 The impact of stress on product recovery rate according to embodiments of this disclosure is illustrated (f R ).

[0030] Figure 17 The effect of desorption pressure on the optimal purge volume (f) according to an embodiment of this disclosure is illustrated. PG ).

[0031] Figure 18 The pressurization / vacuum step time (t) according to the embodiment of this disclosure is described. P and t V The iterative process of ).

[0032] Figure 19 Examples are given regarding product purity and V at a constant product flow rate. CLM The pre-calibration correlation between them.

[0033] Figure 20 The adsorption pressure (P) according to the embodiments of this disclosure is depicted. ads ) and desorption pressure (P) des The iterative process of ).

[0034] Figure 21 and Figure 22 Schematic diagrams of other exemplary oxygen concentrators disclosed herein are depicted. Detailed Implementation

[0035] Exemplary embodiments discussed with reference to the accompanying drawings will now be described in detail. In some instances, the same reference numerals will be used throughout the drawings and in the following description to refer to the same or similar parts. Unless otherwise defined, technical or scientific terms will have the meanings commonly understood by one of ordinary skill in the art. The disclosed embodiments are described in sufficient detail to enable those skilled in the art to practice them. It should be understood that other embodiments may be utilized and changes may be made without departing from the scope of the disclosed embodiments. Therefore, the materials, methods, and embodiments are merely illustrative and are not intended to impose necessary limitations.

[0036] It should be noted that all relative terms (such as “about,” “substantially,” “approximately,” etc.) are used to indicate a possible variation of up to 15% (unless otherwise indicated or specified). For example, parameters described as substantially equal to or about “t” units (e.g., pressure, time, size, etc.) cover a variation of up to 15%. Additionally, described ranges (e.g., XY, X to Y, etc.) include two boundaries. That is, a parameter described as being between about XY units can have any value between X-15% and Y+15%. These small variations are intended to cover deviations that may occur, for example, during manufacturing, processing, and / or operation.

[0037] It should be noted that all of the following terms, including “oxygen concentrate gas,” “oxygen production,” “oxygen product,” “concentrated oxygen,” “oxygen-enriched air,” “oxygen flow,” “oxygen supply,” and “oxygen-enriched gas,” are used to indicate oxygen products passing through a column filled with adsorbent.

[0038] The disclosed systems use pressure swing adsorption (PSA), meaning that the pressure swings from a relatively high pressure that allows the target gas to be adsorbed into the adsorbent material to a relatively low pressure that allows the target gas to be desorbed from the adsorbent material. The disclosed systems may include absolute pressure swing adsorption (APSA), meaning that the process pressure swings between adsorption pressures above atmospheric pressure (e.g., >1 bar) and desorption pressures below atmospheric pressure (e.g., <1 bar under vacuum). In APSA, both pressures are described in an absolute manner (in absolute units of bar). In this document, the terms “absolute pressure swing adsorption” (APSA) and “vacuum pressure swing adsorption” (VPSA) are used interchangeably.

[0039] High-quality oxygen streams can be achieved using PSA and APSA technologies. APSA and PSA are two different methods used in gas separation and purification processes. They both rely on the principle of adsorption to separate gases. One or more columns, which may contain adsorbents such as zeolite, are pressurized alternately by a pump, preferably adsorbing N2 from the feed air and allowing oxygen to pass through as the product. At the end of the production cycle, the higher column pressure is released to ambient pressure or below atmospheric pressure, during which time the adsorbed N2 is also released. Simultaneously, the column is purged using the oxygen product from another column, leaving a relatively clean batch of zeolite ready to begin the next cycle.

[0040] APSA System

[0041] APSA technology incorporates a vacuum pump to increase the pressure swing range by utilizing pressures below atmospheric pressure. It offers several significant advantages over PSA technology, including: (1) The adsorbents commonly used in portable oxygen concentrators (LiX or LiLSX zeolites) have steep N2 isotherm curves over the sub-atmospheric pressure range, meaning a larger working adsorption capacity for the same pressure swing. APSA utilizes this steep segment of the isotherm curve, resulting in higher efficiency in adsorbent utilization (lower bed size factor). This leads to smaller columns and lower costs associated with the adsorbent. (2) APSA technology widens the pressure swing range by reducing the desorption pressure, rather than increasing the adsorption pressure as in the case of PSA technology. To achieve the same yield, the adsorption pressure required by the APSA process is significantly lower than that required by the PSA process. Therefore, the pressure ratings of all fluid components are significantly reduced, meaning the device can be smaller and lighter. (3) APSA technology doubles the oxygen recovery rate of the process, meaning that only half the feed air velocity is required for the PSA process. As a result, the adsorbent is exposed to fewer pollutants (mainly moisture and CO2 from ambient air) and will have a longer run time. (4) The lower feed required in APSA technology introduces a significantly lower pressure drop on the zeolite adsorbent column. This means that the pressure pump operates at a much lower back pressure, thus allowing more feed to be delivered at the same target adsorption pressure. (5) APSA technology reduces the zeolite column pressure to below atmospheric pressure in each cycle. Desorption is more complete, resulting in less residual N2. The process also cleans the column better.

[0042] APSA systems are conventionally used in various industrial-scale adsorption processes. In this disclosure, APSA-based systems are used in portable oxygen concentrators. In some embodiments, the oxygen concentrator of this disclosure can be a portable device. A portable device (or system) is a device that can be carried, moved, or transported from one place to another without significant difficulty. Portable devices can be carried by a person or transported from one place to another using relatively simple means, such as by hand, trolley, bag, vehicle, or other mechanism. Portable devices are generally designed to be lightweight, compact, and easy to move, thereby allowing them to be used in a variety of locations or situations as needed.

[0043] In some embodiments, the oxygen concentrator of this disclosure may be a handheld device. A handheld device is a type of portable device that can be carried from one place to another by a person (user, clinician, technician, etc.). The handheld device may be worn on a person's belt, placed in a bag, backpack, handbag, or purse, hung on a strap across a person's shoulder or behind their neck, or strapped to a person's arm or leg. In some embodiments, the handheld device may be worn on a person's arm or leg via at least one of a silicone strap, a sports strap, a sleeve strap, and a spandex strap. This strap can hold the handheld oxygen concentrator in place. In some embodiments, such devices may be designed to be held and operated with one or two hands. These devices are typically compact and lightweight, making them easy to carry and use while on the move. While handheld devices are a subset of portable devices, not all portable devices are designed to be held in the hand and operated directly like handheld devices. Portable devices may have different user interfaces and interaction methods compared to handheld devices. In summary, one difference between handheld devices and portable devices lies in the intended manner of use and interaction. Handheld devices are specifically designed to be operated while held in the hand, while portable devices, although also designed for mobility, encompass a wider range of transportable devices that may not necessarily require handheld operation.

[0044] There is a great need for oxygen concentrators that are small and lightweight enough to be portable anywhere and easy to use while still being able to concentrate sufficient oxygen. Current oxygen concentrators employ many trade-offs that harm the user or patient in order to achieve adequate oxygen output. To obtain sufficient oxygen output, current oxygen concentrators increase adsorption pressure by increasing the amount of zeolite, by increasing the size of the pump, or by increasing the number of pumps. These result in increased power requirements for the device, which reduces uptime, and / or increases the number of components, thereby increasing costs for the user, and making the oxygen concentrator heavier, larger, and more cumbersome.

[0045] Handheld oxygen concentrators can be used to treat acute attacks of chronic headaches. The inhaled oxygen delivered through this portable device provides rapid relief during acute attacks of cluster headaches and migraines. In addition to headache management, supplemental oxygen delivered by the handheld oxygen concentrator can also play a role in wound healing, ensuring that living tissue receives the oxygen needed to regenerate healthy tissue and promote faster recovery. Additionally, the handheld oxygen generator of this disclosure can be used as part of first aid, providing immediate oxygen support in emergency situations to address a range of medical needs. Living tissue requires oxygen and nutrients to thrive, and for wounds, oxygen is essential for regenerating healthy tissue. In normal wound healing, this process alternates between hypoxic and normoxic conditions, which is critical at all stages of healing. The oxygen supply to wound tissue, determined by pulmonary gas exchange and blood hemoglobin levels, plays a major role in the reconstruction of new blood vessels and connective tissue, as well as epithelial cell migration. Oxygen also promotes normal local metabolism and enhances resistance to infection. The handheld oxygen generator of this disclosure is particularly beneficial in these applications. It provides a portable and convenient means of delivering oxygen where it is most needed, whether for treating headaches or supporting wound healing. In the context of wound care, handheld devices can be used for topical oxygen therapy (TOT), a set of techniques that deliver oxygen directly to wounds or ulcers to promote tissue healing. The handheld oxygen concentrators of this disclosure can be used to increase oxygen tension and support tissue regeneration. Unlike hyperbaric oxygen, rapid oxygen delivery has a significant positive impact on wound healing; handheld oxygen concentrators can be quickly applied to wound dressings, saturating them with high-purity oxygen, or used to supply oxygen to higher circulation or low-pressure bags or bandages, ensuring continuous oxygen delivery to the wound site and promoting faster recovery and accelerated healing. The handheld oxygen generators of this disclosure can more efficiently generate a high-purity oxygen stream from ambient air by utilizing the adsorption capacity of zeolite particles in a more compact and portable design, and can operate continuously, allowing for a stable supply of purified gas without frequent interruptions or restrictions on mobility, and enhancing the effectiveness of oxygen therapy for managing acute headache attacks, especially in portable and emergency situations. They can also be customized for different gas compositions. Other portable and handheld applications include remote or temporary gas supply systems, where the device can be deployed in remote locations or areas where access to a stable field gas supply is limited, eliminating the need for gas transport and storage logistics. This could be particularly valuable for military forces deployed in remote areas or active conflict zones, providing self-sufficient gas supplies for a variety of needs, replacing bulky oxygen cylinders and large oxygen production equipment in field hospitals, during casualty evacuations, on the road, and on the battlefield.Handheld devices are suitable for drone deployment or airdrop, ensuring rapid and flexible deployment to personnel in critical situations and emergency responses or mobile medical services. These rapidly deployable units provide oxygen to medical facilities or various military operations and emergencies, operating with multiple power sources, including AC, DC, and rechargeable batteries, ensuring continuous operation in diverse environments. Biogas purification or mining operations can be used to generate oxygen or nitrogen for ventilation, inerting, or treatment applications. In veterinary clinics, handheld oxygen concentrators allow for a higher level of personalized animal care, where adequate oxygen supply is crucial for successful treatment and recovery. Any terrestrial or marine mammal, due to its size, location, and handling difficulties, may require oxygen outside of the normal veterinary clinic and in its environment. For example, racehorses suffering from severe exercise-induced pulmonary hemorrhage (EIPH) can benefit from oxygen therapy. EIPH occurs when small blood vessels in the lungs rupture during strenuous exercise, causing blood to enter the airways. This condition can lead to breathing difficulties, low oxygen levels, and poor overall performance in horses. Administering supplemental oxygen via a handheld oxygen concentrator can help stabilize horses by increasing blood oxygen levels, promoting faster recovery, and reducing the risk of further complications. This therapy can also be crucial during transport to a veterinary clinic or while awaiting more intensive medical treatment. Handheld oxygen concentrators are seamlessly portable and integrate into existing veterinary clinic setups, continuously producing oxygen, eliminating the need for inventory management and minimizing downtime.

[0046] In some embodiments, releasing the higher column pressure to the lower pressure after an equilibrium cycle can be achieved through a single-stage process. For example, once the equilibrium cycle is complete, the adsorbent column is connected to ambient air. In some embodiments, releasing the higher column pressure to the lower pressure can be achieved through a two-stage process. For example, once the equilibrium cycle is complete, the adsorbent column is first connected to ambient air to allow the higher pressure in the adsorbent column to decrease to a lower pressure (e.g., approximately 1 atmosphere). This step is referred to as “positive pressure release.” The adsorbent column can then be connected to a vacuum pump, which further reduces the pressure (e.g., to between approximately 0.3 bar and 0.7 bar). Reducing the desorption pressure in this way is beneficial because it enhances the desorption of residual N2 and reduces the oxygen purging time. This shorter purging duration requires less oxygen to purge the nitrogen column because the receiving column is at a lower pressure and allows for a shorter cycle time. In some embodiments, reducing the column pressure from a higher level to a lower level can be achieved through a two-stage process operating in parallel. As an example, upon completion of the equilibrium cycle, the adsorbent column can be vented to the surrounding atmosphere while simultaneously connected to a vacuum pump.

[0047] Using the same adsorption pressure, feed volume, and amount of adsorbent, the exemplary benchtop prototype of the disclosed oxygen concentrator produces up to approximately 59% more oxygen product. Oxygen recovery rate, defined as the ratio of product oxygen output to feed oxygen, is an important parameter for comparing the efficiency of the feed stream and the adsorption process. Due to size and maximum adsorption pressure limitations, portable oxygen concentrators typically have a recovery rate of 30%–35%. Some embodiments of the disclosed oxygen concentrator achieve a recovery rate of 54%. Additional adjustments, such as using a more powerful vacuum pump, can achieve even higher recovery rates.

[0048] Six-step APSA

[0049] Figure 1 An exemplary two-column system flow diagram of an oxygen concentrator according to some embodiments of this disclosure is depicted. Figure 1 As shown, system 100 may include a pressure pump 102, a vacuum pump 104, two zeolite-containing columns 110 and 120, a vacuum storage tank 106, a product oxygen tank (or oxygen storage tank) 130, and multiple valves, manifolds, and sensors to provide concentrated oxygen gas from air. It should be noted that... Figure 1 Exemplary implementations have been illustrated, and several variations are possible. For example, Figure 1 The components depicted are merely exemplary, and other embodiments of the disclosed system may have additional or fewer components. For example, in some embodiments, different numbers and / or types of valves may be used. As another example, in some embodiments, more than two adsorbent columns may be used.

[0050] In some embodiments, system 100 may include a controller (not shown) configured to control the sequence and flow of steps in the oxygen concentrator system. The controller may control the opening and closing of gas inlets, outlets, and multiple valves, as well as the timing of opening and closing these components. The controller may control the pressure and gas flow rate of at least two columns containing the adsorbent. The controller may be configured to control the pressure and gas flow rate of oxygen tank 130 and vacuum storage tank 106. In some embodiments, pressure variations and gas flow rates between different sequences and steps may be controlled by the controller.

[0051] In some embodiments, inlet air (e.g., atmospheric air, indoor air, air from a tank, or air from any other air source) is introduced into system 100 through inlet 10. The inlet air may consist primarily of nitrogen and oxygen. In some embodiments, the inlet air may be compressed in pressure pump 102 before being delivered to columns 110, 120. System 100 may separate nitrogen from oxygen and deliver air with a higher oxygen concentration (e.g., approximately 85%-96% oxygen in some embodiments) out of system 100 to the user via outlet 140. Although an oxygen concentrator is described herein, generally, system 100 (with suitable modifications) can be used to separate any type of gas molecules from feed air. In other words, in some other embodiments, system 100 may separate different types of gas molecules from feed gas and deliver purified gas out of system 100 to the user via outlet 140.

[0052] like Figure 1 As schematically illustrated, system 100 may include a pair of columns 110, 120 that help separate nitrogen from inlet air. Columns 110 and 120 may contain an adsorbent (e.g., zeolite). Zeolites are a group of naturally occurring minerals and synthetic compounds with unique crystal structures. They are often referred to as “molecular sieves” because they can selectively adsorb and trap molecules based on size and shape. Zeolites consist primarily of aluminum, silicon, and oxygen atoms arranged in a three-dimensional framework with regularly spaced pores and channels. Air may be drawn in, filtered, compressed, and directed to one of columns 110, 120 through inlet 10. Each column may include a feed end 112, 122 that receives feed air from inlet 10, the feed air passing through a pressure pump 102, a flow sensor FS1, a pressure sensor PS1, and a valve V1 or V4. In some embodiments, the feed ends of columns 110, 120 may also include outlets 30, 40 (respectively) for discharging the gas into the environment. Each column 110, 120 also includes product ends 114, 124, which can direct purified product gas (such as oxygen) to oxygen tank 130 or user 140.

[0053] Figure 2 It is used for Figure 1A schematic diagram of an exemplary cycling sequence and steps for an exemplary dual-column system is provided. The cycling phase for one column includes the following steps: Step 1 - Pressurization (PR); Step 2 - Production and Purging (PD / PG); Step 3 - Equalization (EQ); Step 4 - Depressurization (BD); Step 5 - Vacuum and Receiving Purging (VU / RPG); and Step 6 - Equalization (EQ). In some embodiments, the cycle time for completing one round of all six steps for one column can be between approximately 2 seconds and 15 seconds or 5 seconds and 12 seconds (based on the selected parameters). In some embodiments, the cycle time for one column can be approximately 9.4 seconds. The disclosed oxygen concentrator system can achieve shorter cycle times using smaller zeolite adsorbent particle sizes (such as less than approximately 1 mm). The disclosed oxygen concentrator system results in higher productivity and is more suitable for small, handheld, portable, and non-stationary installations.

[0054] In some implementations, during the pressurization step (step 1), for column 110, refer to Figure 1 The double-column configuration and Figure 2 In the sequence and steps, inlet air (including oxygen and nitrogen) can be compressed in pump 102 and then directed to column 110 via valve V1. As the compressed inlet air is directed to column 110, the pressure in column 110 can increase. Pressure changes in column 110 can be monitored by pressure sensor 4. In some embodiments, the pressurization step time can refer to the time spent pressurizing the air in column 110. In some embodiments, the pressurization step time can determine how long the adsorbent column 110 can be pressurized by the inlet air. The inlet air is compressed to a selected adsorption pressure or a predetermined adsorption pressure using pump 102 at a given pressure. In some embodiments, the pressurization step time can be set in the range of about 1 second to 10 seconds or about 2 seconds to 4.8 seconds. In some embodiments, the pressurization step time can be less than about 5 seconds or less than about 3.55 seconds.

[0055] Typically, the adsorption process can be described by the adsorption pressure (P). ads The process is carried out under high pressure, where the feed gas is fed through an adsorbent bed in a column, and some adsorbable gas molecules are captured by the adsorbent. In contrast, the pressure at which the adsorbed gas is released or desorbed is the desorption pressure (P). des In some embodiments, P is used in the disclosed oxygen concentrator system. ads It can be between about 2 bar and 3 bar, or preferably between about 2.4 bar and 2.5 bar. Relatively low P ads It also allows for the delivery of more feed air by a pressure pump at any given pressure. Higher P adsThis results in higher oxygen recovery rates during the process, but high-pressure equipment is typically bulky and heavy. Conventional industrial PSA systems typically use absorption pressures up to about 10 bar; however, in portable devices, especially handheld devices designed for use by mobile individuals, small or micro pressure pumps are required to achieve the adsorption pressure.

[0056] When the pressure in column 110 reaches P ads At this point, step 2 production at column 110 can begin. When column 110 reaches the adsorption pressure, nitrogen in the compressed inlet air can be adsorbed by the adsorbent. The high-pressure oxygen product can flow to product end 114, and can then be delivered to three destinations, including outlet 140 to the user, oxygen tank 130, and column 120.

[0057] In some implementations, the oxygen product can be delivered to outlet 140 upon user triggering, such as during breathing. The oxygen product can be delivered via valve V10. The flow rate and purity of the oxygen gas can be measured by a flow sensor and an oxygen sensor. When the resulting flow rate and purity of the oxygen do not meet predefined requirements, system 100 can adjust the system accordingly.

[0058] In some implementations, oxygen production can be achieved by delivering oxygen to oxygen tank 130 via a pressure difference (referred to as differential pressure) between column 110 and oxygen tank 130. Oxygen tank pressure (P... B ) is like Figure 1 The pressure at oxygen cylinder 130 shown can be maintained above a certain level, such as between about 1.5 bar and 2.5 bar, or preferably between about 1.9 bar and 2.0 bar. In some embodiments, only when the pressure at column 110 exceeds P B Only when the product gas is in use is the flow allowed into oxygen tank 130 permitted. In some embodiments, the start-up and flow rate of oxygen production can be controlled solely by the pressure difference between the column and the oxygen tank. In some embodiments, the pressure regulator and flow controller may not be integrated into system 100, for example, to reduce the size and / or weight of portable or handheld systems. Consistent with the disclosed embodiments, Figure 1 The exemplary oxygen concentrator system illustrated herein can regulate flow rate by using differential pressure, which can be a spontaneous process rather than using pressure regulators and flow controllers.

[0059] In some embodiments, regarding the purging step as part of step 2, a portion of the oxygen product in the production end 114 of column 110 is sent to column 120 as purge gas via valve V9. The purge gas (in some embodiments, may be a portion of the product gas from column 110 and may contain 90% oxygen) is guided through the receiving column (in this case, column 120) to aid in the regeneration of the adsorbent, preparing it for the next cycle. The purging step ensures that high-purity oxygen fills the product end and cleans the adsorbent surface. Figure 1 and Figure 2 In the disclosed oxygen concentrator system, when the receiving column pressure is at P des At this point, purging may occur at the end of the desorption step in the vacuum process. In some embodiments, the purging pressure (P) is... PG The pressure () refers to the pressure of the receiving column, which can be set between about 0.3 bar and 0.8 bar, preferably between about 0.45 bar and 0.55 bar. At this pressure, the required oxygen in the purge gas may be lower because it occurs when the receiving column is at its lowest pressure point in each cycle. Allowing the purge flow through the receiving column increases its pressure only slightly, for example, by 0.05 bar.

[0060] Consistent with the disclosed implementation scheme, the purge volume can be set to approximately 50 std cm. 3 / cycle-100std cm 3 Between cycles, in some embodiments, it is preferably about 75 std cm. 3 / Cycle, this is the purge volume optimized through test results. It has been found that if the purge volume remains constant, changing the purge flow rate or purge time within the range specified below has no significant impact on process production.

[0061] In some implementations, the purge flow rate can be set between 4 standard liters per minute (slpm) and 23 slpm, and the purge time can be set between 0.2 seconds and 1.2 seconds. If the purge volume remains constant, the effect of changing the purge flow rate and purge time on oxygen production within this range is negligible. Furthermore, the purge gas can be delivered via a balancing channel, and therefore... Figure 1 The equalization valve V8 shown is used for control, or the oxygen is delivered via a separate purge channel. Both configurations have been tested and yielded similar results. In some implementations, the oxygen concentrator system can achieve an immediate purge step with a purge time of less than 1 second. Test results indicate that the immediate purge step helps reduce the amount of oxygen product required for purge and shortens the cycle time.

[0062] Consistent with the disclosed implementation, when column 110 performs steps 1 and 2, two discharge steps (steps 4 and 5) occur in column 120. Step 4 is the depressurization step. For column 110, the depressurization step (step 4) occurs after step 3 (equilibrium step). For column 120, as... Figure 2 As shown, a depressurization step (step 4) occurs when column 110 performs step 1 (the production step). As the pressure in column 120 decreases, the adsorbed gas can be released or desorbed from the adsorbent, and at the end of this step, the interior of column 120 can be enriched with nitrogen. In some embodiments, the depressurization step can release the desorbed nitrogen into the environment via outlet 30 through valve V3 (for column 110) or via outlet 40 through valve V6 (for column 120). In step 4, column feed ends 112 and 122 can be opened to the surrounding environment, and the column pressure can be reduced to near ambient pressure, approximately 1.0 bar to 1.2 bar, more preferably 1 bar. The column pressure is then further reduced using a vacuum pump. The depressurization step prevents the vacuum pump from being exposed to positive pressure and helps achieve higher vacuum levels. This benefit was found to be significant in tests where the vacuum pump capacity was significantly smaller than the pressure pump capacity. The depressurization time can be 0.5 to 1.5 seconds, which is sufficient to reduce the column pressure to near ambient pressure. A depressurization step longer than 1.5 seconds is undesirable because it consumes the available vacuum time throughout the entire production cycle, thereby reducing the vacuum level that the process can achieve.

[0063] Step 5 is the vacuum and purge receiving step. During this step, a vacuum pump 104 removes the desorbed gas (e.g., nitrogen) from the column undergoing desorption via valves V2 and V5 (for columns 110 and 120), respectively. Simultaneously, the column undergoing desorption receives purge gas from another column (the column undergoing adsorption). Consistent with the disclosed embodiments, step 5 for column 120 may include venting the desorbed nitrogen via valve V5 using the vacuum pump 104 and receiving oxygen from column 110 as purge gas to clean the adsorbent. The time during which the vacuum pump operates during the vacuum step is referred to as the vacuum step time.

[0064] In this disclosure, it should be noted that steps 4 (depressurization step) and 5 (vacuum and receiving purging step) are performed sequentially. However, it should be noted that this is not the only operating model. In some embodiments, steps 4 and 5 may be performed simultaneously after the equalization cycle. Alternatively, step 4 may be omitted, and step 5 may be performed only after the equalization cycle by directly connecting column 120 to vacuum pump 104. In some other embodiments, step 4 may be performed after the equalization cycle, and column feed ends 112 and 122 may be open to the surrounding environment, while step 5 may be eliminated.

[0065] In some implementation schemes, P desP is the desorption pressure when releasing or desorbing adsorbed gases during the use of an oxygen concentrator system. des The pressure can be between about 0.3 bar and 0.8 bar, preferably between about 0.4 bar and 0.5 bar. In some embodiments, the desorption pressure P des This can be achieved using a miniature vacuum pump. Typically, such miniature vacuum pumps may be difficult to operate below 0.3 bar. Using the disclosed oxygen concentrator system, the miniature vacuum pump reaches the desorption pressure more quickly, matches the required pressurization time more effectively, and keeps the entire cycle time for all six steps below the required maximum, such as approximately 12 seconds for all six steps. Vacuum buffer or vacuum storage tank 106 (see...) Figure 1 This also helps to make the desorption process more efficient and reduce cycle time. For example, see reference... Figure 1 When columns 110 and 120 are not connected to vacuum pump 104 (e.g., during the depressurization step), vacuum pump 104 evacuates vacuum storage tank 104 (e.g., reduces the pressure therein). Therefore, during the vacuum step, when one of these columns 110, 120 is connected to vacuum pump 104 to evacuate the pressure in the column to below atmospheric pressure, the column can be purged more quickly and efficiently.

[0066] In some embodiments, the vacuum step time can be set in the range of about 2.5 seconds to 4.3 seconds, preferably about 3.05 seconds. The selection of the vacuum step time allows the adsorbent column to reach a selected desorption pressure using a given vacuum pump. In some embodiments, the vacuum step time can be slightly shorter than the pressurization time (e.g., about 0.5 seconds less in some embodiments) to accommodate the depressurization step.

[0067] In some implementations, the vacuum release step occurs after the vacuum step. During the vacuum release step, column 110 is opened to the ambient environment at its feed end 112 to raise the pressure to near ambient pressure before the pressurization step occurs. The inclusion of the vacuum release step prevents pressure pump 102 from being exposed to a vacuum. It also helps to achieve higher adsorption pressures. The vacuum release step can be in the range of 0.2 seconds to 0.5 seconds, during which the column pressure increases to near ambient pressure. Vacuum release steps longer than 0.5 seconds result in lower adsorption pressures and thus negatively impact oxygen production.

[0068] In some implementations, step 3 (equilibration step) for columns 110 and 120 may begin when a product gas (such as high-pressure oxygen in column 110) is introduced into column 120 to purge it, and simultaneously, inlet gas enters columns 110 and 120 from inlets 112 and 122 until the pressures between the two columns 110 and 120 are approximately equal. While column 110 is in step 3, column 120 undergoes step 6. When the pressures in the two beds are approximately equal at a predetermined equilibrium pressure, the equilibration step terminates, and the second half of the cycle begins, in which column 120 undergoes steps 1-3, and column 110 undergoes steps 4-6.

[0069] In some implementation schemes, equalization pressure (P) EQ The pressure at the product end of the column at the end of the equalization step is set to between approximately 1.3 bar and 2 bar, preferably between approximately 1.4 bar and 1.5 bar. The equalization step can increase oxygen recovery and reduce power consumption throughout the process. The optimal P for this process was determined. EQ The equilibrium time is 1.4 to 1.5 bar, which implies near-complete equilibrium, and this is known to provide a higher oxygen recovery rate than using incomplete equilibrium. In some embodiments, the equilibrium time can be between about 0.2 and 0.5 seconds, and preferably about 0.45 seconds. Based on test results, gas exchange during the equilibrium step mainly but not completely occurs within the first 0.2 seconds. An equilibrium step shorter than 0.2 seconds is insufficient to achieve optimal P. EQ Equilibrium typically completes within 0.5 seconds, meaning the two columns have reached equal pressure and no further gas exchange occurs. Further increases in equilibrium time negatively impact oxygen production efficiency because they lead to longer cycles.

[0070] Typically, three equalization schemes exist: top-top, bottom-bottom, and cross. The top-top equalization scheme was found to result in the highest oxygen production. Furthermore, during the equalization step, the feed ends 112 and 122 of columns 110 and 120 can be connected to a pressure pump (P), a vacuum pump (V), the ambient environment (A), or it can be sealed (S). Various combinations of these configurations, such as P / P, P / V, A / S, etc., were tested. The optimal combination was found to be P / P and A / P, where the pressure pump delivers feed air to both columns, or the pressure pump delivers feed air to the low-pressure column, and the high-pressure column is open to the ambient environment. In small installations, pump capacity is constrained by size and weight, often limiting factors for process production. Therefore, to maximize output, the pump capacity must be utilized to its maximum potential. The P / P or A / P configuration of column feed ends 112 and 122 ensures that the pressure pump has no idle time. During the equalization step, the low-pressure column is pressurized at both ends—by feed air from feed ends 112 and 122, and by high-purity oxygen exchanged at product ends 114 and 124. Furthermore, in the P / P configuration, the feed air supply mitigates the pressure drop in the high-pressure column, thus reducing the amount of N2 desorbed and transferred to the alternative column.

[0071] In some implementations, the feed flow rate can be an average of about 7 slpm to 8 slpm, which is equivalent to about 300 stdcm. 3 / Cycle to 800 std cm 3 / Circulation. In some cases, a higher feed flow rate may be desirable because columns 110, 120 can be pressurized to a given adsorption pressure in a shorter time, or the columns can reach a higher adsorption pressure within a given step time. The flow rate is the maximum value of currently available off-the-shelf micro pressure pumps within a selected pressure range, which is within P... EQ =1.4 bar and P ads =2.5 bar. Consistent with the disclosed embodiment, the process can be operated with partial feed. During partial feed, when the column pressure reaches a certain P ads Subsequently, a portion of the feed stream can be directed to the exhaust port during the pressurization and / or purging steps. Tests conducted by purging 3%–7% of the feed in each cycle (which allows the adsorption pressure to be maintained at a given level for a longer period) showed no significant impact on production. The column pressure can be controlled by the volume of feed gas in each cycle. The pressure increases with pressurization time as more feed gas is delivered. By using partial feed, the column can be maintained at a given pressure while running for longer cycles.

[0072] Phase 4 APSA

[0073] In an alternative embodiment, the APSA system may include four stages: Stage 1, Stage 2, Stage 3, and Stage 4. Stages 1 and 3 are oxygen production stages, during which oxygen is concentrated at columns 110 and 120, respectively. Columns 110 and 120 are connected to a positive or negative pressure pump, delivering oxygen to a removable module 150 and an output terminal 140. In Stage 1, column 110 undergoes an adsorption process to output concentrated oxygen product, and column 120 undergoes a desorption process to expel saturated nitrogen or adsorbed air filling column 120. During Stage 3, column 110 undergoes a desorption process to expel saturated nitrogen or adsorbed air filling column 110, and column 120 undergoes an adsorption process to output concentrated oxygen product. Stages 2 and 4 are equalization processes, during which system 300 may be configured to equalize the pressure in the two columns. The four stages constitute a cycle of oxygen production. During operation of the portable oxygen concentrator, system 300 may maintain a cycle through these four stages to provide concentrated oxygen.

[0074] Figure 3A A flowchart of stage 1 corresponding to an alternative embodiment of the oxygen concentrator is shown. For example... Figure 3A As shown, the system 300 may include an input terminal 10, a filter 15, a positive pressure pump 102, a negative pressure pump 104, at least two adsorbent columns 110 and 120, an exhaust device 20, a removable module 150, a product output terminal 140, and multiple valves, manifolds, and sensors to provide oxygen-concentrated gas from the air. Figure 3A The components depicted are merely exemplary, and other embodiments of the disclosed system may have additional or fewer components. For example, in some embodiments, different numbers and / or types of valves may be used. As another example, in some embodiments, more than two adsorbent columns may be used. Valves, manifolds, and sensors may provide similar features to those described in the previous embodiments.

[0075] In some embodiments, system 300 may include a controller (not shown) configured to control the sequence and flow of stages in the oxygen concentrator system. The controller may control the opening and closing of gas inlets, outlets, multiple valves, and the timing of opening and closing these components. The controller may include features similar to those described in previous embodiments.

[0076] like Figure 3A As schematically illustrated, system 300 receives inlet air containing approximately 21% oxygen (e.g., atmospheric air, indoor air, air from a tank, or air from any other air source) through inlet 10. The inlet air may be filtered by filter 15 located at inlet 10. In some cases, filter 15 may be a cotton filter. In some embodiments, filter 15 may be an electrostatic and hydrophobic polypropylene material, or any other suitable material.

[0077] During stage 1, column 110 is in the adsorption process, and inlet air can be pressurized in positive pressure pump 102 and directed into column 110 substantially through three-way valve 1. In some embodiments, pressure pump 102, acting as a compressor, is responsible for pressurizing the column to a predetermined level using the flowing pressurized air. Column 110 contains an adsorbent (e.g., zeolite) that can separate the components of the mixture by means of the chemical and physical properties of the components. In some embodiments, column 110 filled with adsorbent (e.g., zeolite) can separate oxygen products from pressurized air containing other gases (e.g., nitrogen). The adsorbent can remove nitrogen from the pressurized air.

[0078] Three-way valve 1 is a valve with three ports. Three-way valve 1 can be used to transfer or switch flow between sources. In some embodiments, during stage 1, three-way valve 1 allows compressed air to pass through and enter column 110, where the air is separated into oxygen and nitrogen by the adsorbent material. Simultaneously, three-way valve 1 can be configured for connection between column 110 and negative pressure pump 104. As we will discuss in stage 3 and... Figure 3B As explained in the text, the three-way valve 1 can open the connection between the column 110 and the negative pressure pump 104, and at the same time close the connection between the column 110 and the positive pressure pump, thereby releasing saturated nitrogen from the column 110 to the exhaust device 20 via the check valve 1.

[0079] In reference phase 1, column 110 is in the adsorption process to output concentrated oxygen to removable module 150. The adsorbent within column 110 adsorbs nitrogen molecules from the feed, producing a product with an oxygen-rich concentration and a purity level exceeding 90%. The concentrated oxygen product can then be transferred from column 110 to removable module 150 via check valve 2. The concentrated oxygen product can be stored in removable module 150 and ultimately directed to output 140 corresponding to the user's inhalation. Simultaneously, during the adsorption process, adsorbed nitrogen is collected in column 110.

[0080] During stage 1, column 120 undergoes a desorption process facilitated by its connection to negative pressure pump 104 via three-way valve 2. Three-way valve 2 opens both ports between column 120 and negative pressure pump 104 while simultaneously closing the connection to positive pressure pump 102. Negative pressure pump 104 generates pressure conditions below atmospheric pressure, where the pressure inside the closed system 300 is lower than the external atmospheric pressure. This creates a suction or vacuum effect, the basis of various types of vacuum pumps. By utilizing this sub-atmospheric pressure, nitrogen previously adsorbed in column 120 during the adsorption process can be effectively extracted through the vacuum line and ultimately discharged through exhaust device 20.

[0081] Considering the high positive pressure in the column at the start of the desorption process, check valve 1 can be used to protect the negative pressure pump 104. Sometimes, maintaining positive pressure can damage the negative pressure pump 104 due to the significant pressure difference between the column and the negative pressure pump 104. Placing check valve 1 next to the negative pressure pump 104 can mitigate this risk by releasing the high pressure in the column after the adsorption process.

[0082] Pressure sensor 1 can be used to monitor the pressure of the vacuum line or column connected to negative pressure pump 104 at any given time. Pressure sensor 1 can also be configured to monitor the desorption pressure achieved by the column, detect vacuum leaks, and predict column life. As the column reaches a deeper vacuum, the adsorbent becomes cleaner and can adsorb more nitrogen in the next cycle. The duration of the desorption process is determined by the adsorption process, which is based on the time taken to reach a predetermined target adsorption pressure. The negative pressure monitored by pressure sensor 1 indicates the degree of “cleanliness” of the column at the end of the desorption process. Therefore, the negative pressure measurement result is one of the key factors in the automated algorithm used to determine the column life, as explained below. Pressure sensor 1 can also detect negative pressure leaks when the column fails to reach the expected negative pressure level corresponding to the duration of time it receives the negative pressure pump.

[0083] Figure 3B A flowchart corresponding to stage 3 of the oxygen concentrator is illustrated. In stage 3, the connection between column 110 and positive pressure pump 102 is closed, and the connection between column 110 and negative pressure pump 104 is opened via three-way valve 1. Similar to column 120 in stage 1, column 110 can undergo a desorption process, whereby nitrogen gas previously adsorbed in column 110 during the adsorption process in stage 1 can be effectively extracted by the negative pressure provided by negative pressure pump 104 and finally discharged through exhaust device 20.

[0084] like Figure 3B As shown, column 120 can be configured to be connected to positive pressure pump 102 via three-way valve 2, while the connection between column 120 and negative pressure pump 104 remains closed. During stage 3, column 120 undergoes an adsorption process by receiving pressurized input air from positive pressure pump 102. The adsorbent (such as zeolite) contained within column 120 effectively separates oxygen from the input air and outputs concentrated oxygen to removable module 150. Simultaneously, the adsorbent adsorbs nitrogen. During the adsorption process, the adsorbed nitrogen can be collected in column 120.

[0085] Figure 4Stages 2 and 4 (equilibrium process) are illustrated to equalize the pressure in the two columns. By implementing the equilibrium process, system 300 reduces the time required for the columns to reach a predetermined target adsorption pressure. The duration of stages 2 and 4 is typically less than one second. During the equilibrium process, both columns 110 and 120 are connected to the positive pressure pump 102, while their connection to the negative pressure pump remains closed. The outputs of columns 110 and 120 can be configured to connect to each other via a two-way valve. The two-way valve can be opened only during the equilibrium process of stages 2 and 4. During stages 1 and 3, the two-way valve between columns 110 and 120 remains closed.

[0086] Removable module

[0087] In some embodiments, a removable module within the disclosed oxygen concentrator can be used to receive concentrated oxygen from the column. For reasons related to patient needs, product upgrades, or user convenience, the removable module can be used to facilitate modification, purification, or replacement of components within the module. Specifically, the removable module can be configured to increase oxygen purity and regulate the oxygen flow to the user.

[0088] Figure 5A A schematic flowchart illustrating a removable module of an oxygen concentrator according to this disclosure is shown. Figure 5A As shown, consistent with the disclosed embodiments, the removable module 150 may include a product buffer 510, a filter 520, an orifice 530, an oxygen sensor 540, at least one oxygen reservoir 550, a check valve 560, and a nasal cannula 570.

[0089] In some embodiments, the product buffer 510 may be configured to contain an adsorbent material, such as zeolite, to increase storage capacity and further enhance the purity of the oxygen product after the initial adsorption process occurring in the adsorbent-filled column. Materials used to fill the product buffer 510 may include molecular sieves; activated carbon, silver and copper-based adsorbents, perovskite oxides, polymer membranes, zirconium-based adsorbents, etc. Furthermore, the product buffer 510 can play a significant role in facilitating the flow of concentrated oxygen. Calibrating the product buffer, including the amount of adsorbent used, helps prevent the buffer from becoming saturated with oxygen product and depleted before being delivered to the user. Such balancing helps maintain a consistent oxygen flow, which is important for medical and industrial applications. In some embodiments, the adsorbent-filled product buffer 510 may be able to stabilize the flow rate of oxygen-enriched air. The flow rate of concentrated oxygen through the adsorbent-filled product buffer 510 may be more stable than when it bypasses the product buffer 510.

[0090] In some implementations, filter 520 can capture particulate matter and contaminants that may be generated within the system or enter from external sources. Filter 520 is used to facilitate seamless and efficient operation while protecting users from inhaling these harmful substances. Filter 520 can filter out zeolite leakage from the product buffer. Filter 520 can be made of any type of material, such as biocompatible filter media, cotton, etc.

[0091] like Figure 5A As shown, orifice 530 can be a precisely sized orifice that restricts the flow of concentrated oxygen. Specifically, orifice 530 can act as a precise flow regulator, allowing a specific amount of oxygen to flow while also measuring flow rate, reducing pressure, or restricting flow.

[0092] In some implementations, the oxygen sensor 540 can be used to measure the percentage of oxygen after it has flowed through the orifice 530 but before it enters the oxygen reservoir 550. Measuring the oxygen percentage ensures that the amount of oxygen administered to the patient is within the user-specified required or predetermined range. The oxygen sensor 540 can be programmed to activate an alarm to notify the user upon detecting a low oxygen percentage. This alarm can take any form, such as sound, light, a message on the user interface, etc.

[0093] In some implementations, the oxygen reservoir 550 may be in the form of a balloon or a similar plastic bag material. The oxygen reservoir 550 may be configured to be inflated with a low-pressure oxygen stream and to expand as it is filled with oxygen product during the user's exhalation, and then deflate during the user's inhalation. Figure 5B and Figure 5C Two exemplary embodiments of oxygen storage devices 550' and 550'' are described in the document.

[0094] like Figure 5BAs shown, the oxygen reservoir 550' can be an inflatable sac-like container capable of being extended from a single point or a separate junction in the oxygen concentrator's flow path. In some embodiments, the single point can be a single circular point. In some embodiments, the single circular point may include inflatable material. In some embodiments, the single point or junction may be located between the oxygen sensor 540 and the check valve 560, which is located before the nasal cannula 570. The flow path can be a conduit through which oxygen products flow between the oxygen sensor 540 and the check valve 560. In some embodiments, the flow path can connect different components within the removable module 150. In some embodiments, the flow path can be a conduit including a section of inflatable material. The inflatable material can be made of a flexible and elastic material that can be inflated or deflated as needed. The inflatable material can be made of any suitable material, such as rubber, plastic, or other similar materials. The inflatable material can be designed to inflate to a predetermined size and shape, which may be determined based on the specific application or use of the flow path. Additionally, the inflatable material can be deflated when not in use, which can help reduce the overall size of the flow path and storage requirements.

[0095] In alternative implementation schemes, such as Figure 5C As shown, the oxygen reservoir 550'' may include an expandable, balloon-like material seamlessly integrated into a flow path tube for concentrated oxygen. The flow path tube may include at least two different materials, one of which is a balloon-like material that inflates during the user's exhalation. This balloon-like material may be configured to connect to another tubular plastic material having limited inflatability or shape-changing properties, or no inflatability or shape-changing properties.

[0096] In some other implementations, such as Figure 5D As shown, the oxygen reservoir 550''' may include an expandable sac-like material that can be inflated from the connection point of the main flow path. The flow path may have a reduced internal path diameter or a reduced cross-sectional area around the opening of the oxygen reservoir 550'''. This narrower flow path facilitates the passage of oxygen product around the oxygen reservoir 550''', creating a Venturi effect. As fluid flows through the reduced cross-sectional area of ​​the pipe, conduit, or channel, its velocity increases, resulting in a pressure decrease (vacuum). This pressure decrease draws oxygen stored in the oxygen reservoir 550''' to merge with the oxygen product flow. The diameter of the passage can be adjusted to have a minimum or negligible vacuum pressure under normal oxygen output flow, so that it does not impede the "filling" of oxygen in the oxygen reservoir 550'''. When a user inhales, the Venturi effect may become significant as the flow rate of oxygen product through the narrow path increases. This can create a vacuum effect, drawing oxygen stored in the reservoir.

[0097] In some implementations, the check valve 560 may be in the form of a duckbill check valve. For example... Figure 5B and Figure 5C As shown, the check valve 560 can be positioned downstream of the oxygen reservoir 550 and serves as a one-way conduit for further delivery of oxygen to the patient via the nasal cannula 570. By effectively impeding the user's exhalation and preventing contaminants from entering the removable reservoir 150, the valve ensures the purity and effectiveness of the oxygen supply. In some embodiments, such as Figure 5B and Figure 5C As shown, check valve 560 is located at a more distal position along the flow path. It is noteworthy that check valve 560 does not cover or obstruct the filling orifice of oxygen reservoir 550, nor does it obstruct the interconnection or mass exchange area between oxygen reservoir 550 and the flow path. In some embodiments, the filling orifice of oxygen reservoir 550 may refer to the opening through which oxygen product is filled into the reservoir. Additionally, in some embodiments, a single check valve 560 located at a distal point downstream along the flow path can regulate multiple oxygen reservoirs 550 located upstream along the flow path.

[0098] In some implementations, check valve 560 may require an opening pressure to allow oxygen product to flow through it. The opening pressure can be defined as the pressure of the oxygen product flow that allows the valve to open. In some implementations, the opening pressure is the pressure difference between the inlet and outlet ports of the valve when flow is first detected on the output side. The opening pressure can create a slight back pressure, forcing the oxygen product in the flow path to first fill and expand the oxygen reservoir 550. Once the oxygen reservoir 550 is filled and the accumulated pressure may have reached the opening pressure, the oxygen product can be forced through check valve 560. As a result, oxygen product from this source can bypass the oxygen reservoir 550 and flow to the nasal cannula 570 and outlet 140.

[0099] In some embodiments, the user's inhalation can create negative pressure or vacuum on the nasal cannula 570. Suction promotes the flow of oxygen product from the oxygen reservoir 550 into the nasal cannula 570, thereby depleting the oxygen reservoir 550. In some embodiments, a one-way check valve 560 may be configured to prevent contaminants from the user's exhalation, such as CO2, bacteria, and moisture, from entering the oxygen reservoir 550 and diluting the oxygen concentration therein. Furthermore, preventing moisture reduces the risk of biological organism growth inside the oxygen reservoir 550, thus reducing the frequency of replacement of the removable module 150. A UV-C LED lamp (not shown) may be added to sterilize contaminants in the oxygen reservoir 550.

[0100] The removable module 150 can be replaced periodically. In some implementations, the replacement frequency can vary, ranging from daily, weekly to every six months or year, and optionally every two or three weeks, one month, two months, three months, four or five months, every six months or year. Additionally, the replaceable removable module 150 can be available in various models, each with its own product buffer size, adsorption capacity in the product buffer 510, oxygen storage capacity, and oxygen reservoir 550 quantity. This allows the user or patient to select the model best suited to their needs.

[0101] like Figures 3A-4 As shown, pressure sensor 2 is located adjacent to removable module 150. More specifically, pressure sensor 2 is positioned adjacent to product buffer 510 filled with adsorbent. Pressure sensor 2 can be used to measure the pressure flowing from adsorbent columns 110, 120 into product buffer 510 within the removable module. In some embodiments, pressure sensor 2 can detect a low rate of pressure change near the inlet of product buffer 510, indicating a high oxygen storage capacity at product buffer 510. On the other hand, a high rate of pressure change detected by pressure sensor 2 adjacent to the inlet of product buffer 510 can indicate a low oxygen storage capacity at product buffer 510, thereby indicating that product buffer 510 is approaching the time when it needs to be replaced.

[0102] Figure 5E A diagram depicting the removable module is shown, highlighting the components used for measurement. Figure 5A The first and second measurement points of oxygen product flow rate in the exemplary oxygen concentrator depicted are shown in the image. Figure 5E As shown, the first point occurs before the oxygen product is introduced into the oxygen reservoir 550. On the other hand, the second point occurs after the oxygen product has passed through the oxygen reservoir 550, check valve 560, and nasal cannula 570. The measurement result of the first point is... Figure 6 Example in the middle; while the measurement result of the second point is in Figure 7 Examples in (c), (d) and (e).

[0103] Figure 6 An exemplary oxygen product flow rate measured at a first point on the removable module 150 is depicted. Figure 6 As shown, oxygen flow rate may exhibit fluctuations. To better understand the reasons behind these fluctuations, the flow is divided into different regions: a, b, c, d, e, and f.

[0104] In region a (stage 1), column 110 undergoes an adsorption process, wherein the pressure within column 110 is gradually increased until a predetermined target adsorption pressure is reached, preferably in the range of 1.7 bar to 3 bar absolute pressure. Simultaneously, product buffer 510 temporarily stores oxygen product. Orifice 530 can be used to restrict the downstream flow of oxygen product to output 140. In some embodiments, orifice 530 can be calibrated to maintain an average output of 1 LPM throughout the APSA process.

[0105] In zone b (stage 2), columns 110 and 120 undergo an equalization process to equalize the pressure between the two columns. During this process, the two-way valves connecting the two outputs of columns 110 and 120 open, causing a momentary drop in pressure in column 110. As a result, the pressure in the column will be lower than the pressure in the product buffer. Due to the pressure difference, check valve 2 at the output of column 110 is now closed. Therefore, the output flow rate begins to decrease during zone b. This rate of decrease may be affected by the amount of oxygen stored in product buffer 510, where a larger product buffer capacity results in a slower decrease and smaller output fluctuations.

[0106] In region c (stage 3), the equilibration process ends. At this point, column 120 is ready to undergo the adsorption process. While the pressure in column 120 remains lower than the pressure in product buffer 510, check valve 3 remains closed. Therefore, no new oxygen product is delivered to product buffer 510. The output flow gradually decreases, maintained by the oxygen stored in product buffer 510.

[0107] As column 120 continues to build pressure, it may eventually exceed the opening pressure of check valve 3, causing a transition to a new region d still in stage 3, involving adsorption and production by column 120. Once this occurs, column 120 will begin delivering oxygen product to product buffer 510 until it reaches the target adsorption pressure.

[0108] In zone e (stage 4), the process of equilibrating the two columns restarts. As in zone b above, the two-way valves connecting the two output ends of the columns for equilibration are opened. Once the two-way valves are open, the pressure in column 120 immediately decreases, thereby closing check valve 3 due to the pressure differential. The output flow is maintained by the oxygen product stored in product buffer 510.

[0109] In zone f (stage 1), column 110 begins the adsorption process again. During this period, because the pressure in column 110 is lower than the pressure in product buffer 510, check valve 2 associated with product output remains closed. Column 110 can build up pressure until it exceeds the opening pressure of check valve 2, after which we continue repeating zone a.

[0110] Figure 7Exemplary oxygen product output measured at a second point under various conditions is depicted, this second point being located where the oxygen product has traveled through Figure 5E The removable module is followed by the oxygen reservoir 550, check valve 560, and nasal cannula 570. The gray shaded area represents the oxygen product discharged from the device output 140. Output (a) depicts an optimal scenario where the additional storage capacity of the oxygen reservoir 550 and the opening mechanism of the check valve 560 correspond to the user's breathing pattern, thereby allowing the removable module 150 to dispense oxygen product without any waste during exhalation or when triggered by an additional electronic device.

[0111] In some implementations, as shown in output (b), if no breathing is detected for a certain duration, the oxygen reservoir 550 will become fully filled, and the accumulated oxygen product before the check valve 560 will exceed the opening pressure. As a result, the oxygen product will flow directly through the nasal cannula in a continuous manner.

[0112] In some implementations, oxygen output may be affected by various factors, including the oxygen storage capacity of the oxygen reservoir 550, the opening pressure of the check valve 560, the expiratory pressure of the user at the user end of the nasal cannula 570, and the duration of the user's exhalation. If the user's expiratory duration is long enough and the oxygen reservoir 550 is fully filled, the pressure of the accumulated oxygen product before the check valve 560 may exceed the opening pressure, causing oxygen to exceed the check valve before the user inhales, such as... Figure 7 The output (c) depicts this.

[0113] In some embodiments, the portable oxygen concentrator may include a removable module 150 that can be attached to the concentrator body, which includes a column, pump, battery, valve, conduit, and other necessary components. Alternatively, in some embodiments, the removable module 150 may be optionally connected to the body of the portable oxygen concentrator, or may extend away from the body using a retractable oxygen supply tube.

[0114] In this particular embodiment, the removable module 150 is integrated by connecting it to a portable oxygen concentrator employing a four-stage absolute pressure swing adsorption (ABS) system. However, it is worth noting that alternative systems, including six-step ABS, pressure swing adsorption (PSA), vacuum PSA, or any other oxygen adsorption system, may also be attached to the removable module 150.

[0115] Pumps and pump buffers

[0116] In some implementations, the capacity of the pressure pump is in the range of 6 slpm to 11 slpm at a pressure range of 1.4 bar to 2.5 bar. Given a specific amount of zeolite adsorbent and flow rate, the pressure pump can achieve a flow rate of P... EQ With Pads The gas is delivered to the adsorbent column under pressure, in conjunction with the selection of the circulation time. The circulation time reflects the number of cycles per minute and affects production levels in conjunction with the feed flow rate. The operating pressure range of the pressure pump (ΔP) is defined as the difference between the equilibrium pressure and the adsorption pressure in the disclosed oxygen concentrator system. ΔP = Pads - P EQ The aforementioned capacity combination (averaging 6 slpm to 11 slpm at 1.4 bar to 2.5 bar) is optimal for oxygen concentrator systems within the constraints of available equipment.

[0117] In some exemplary embodiments, the capacity of vacuum pump 104 can be set between 3 slpm and 14 slpm within a pressure range of 0.3 bar to 1.0 bar. The achievable vacuum level is positively correlated with the vacuum pump capacity. The specified capacity is the minimum required to achieve the stated oxygen production. In some embodiments, a vacuum pump with a higher capacity may be used in the disclosed system.

[0118] In some implementation schemes, such as Figures 8A-8B As shown, an oxygen concentrator system can be configured to use a single pump that provides positive pressure flow and vacuum venting. A suitable pump needs to be selected to meet the required pressure and vacuum capacity. The sequence of steps needs to be adjusted so that the pressurization and vacuuming steps do not overlap. The use of a single pump allows for smaller, lighter, and more energy-efficient portable devices. Three examples of incorporating dual-pump systems into the disclosed oxygen concentrator system are presented.

[0119] Figure 8A An exemplary setup using a dual-head pump as two separate pumps for pressure and vacuum is depicted. In this configuration, one head of the pump supplies pressurized gas to the oxygen concentrator system (the inlet is connected to the ambient environment to draw in fresh air); the other head of the pump provides vacuum suction to extract waste gas from the oxygen concentrator system (the waste gas is discharged through an outlet connected to the ambient environment). In this setup, the pressure and vacuum sides are completely separated and do not interfere with each other. Therefore, the dual-head pump supplies both pressure and vacuum simultaneously.

[0120] Figure 8B An exemplary setup using a dual-head pump as a single pump to provide either pressure or vacuum at any given time is depicted. The dual-head pump functions as a single pump, with two inlets connected as a single inlet (which draws exhaust gas from the oxygen concentrator system); and two outlets connected as a single outlet (which delivers pressurized gas to the oxygen concentrator system). At any given moment, the pump provides either pressurized gas or vacuum, but not simultaneously. The sequence of the circulation phases must be designed in such a way that the pressurization and vacuum phases do not overlap. To prevent exhaust gas recirculation into the oxygen concentrator system, two valves are implemented to communicate with the ambient environment. When the pump is used to deliver pressurized gas, as... Figure 5BAs shown, vent valve 2 is opened to allow fresh air to be introduced into the process. When the pump is used for vacuum, vent valve 1 is opened to allow exhaust gas to be extracted from the process. At the start of the vacuum phase, it may be beneficial to briefly overlap pressurization and vacuum while simultaneously closing vent valves 1 and 2. During this short period, the adsorbent column undergoing vacuum still has relatively high pressure. The exhaust gas can have relatively high purity and can potentially be pressurized and recirculated to an alternative column. The overlap phase can serve as a secondary equalization step, or even replace the equalization step and / or purging step.

[0121] In another embodiment, a single dual-head pump can be used to provide pressure or vacuum at any given time, coupled to a single adsorbent column. This setup is related to... Figure 1 The setup is the same as illustrated in Figure 3, but only one adsorbent column is used in the oxygen concentrator system instead of two. Due to the single pump setup, the pump can only provide pressure or vacuum at any given time. This means that while one column is under pressure or vacuum, the other column must be in idle mode, resulting in longer cycle times than necessary. This problem is solved by using a single column instead of two. As disclosed herein, purging and equalization can be performed using gas from an oxygen tank instead of gas from an alternative adsorbent column. Therefore, the oxygen concentrator system can be operated entirely with a single column and oxygen tank. The advantages of a single column include reduced device size and weight, as well as simplified manufacturing.

[0122] Consistent with the disclosed embodiments, the oxygen concentrator system includes a vacuum storage tank 106 to store vacuum capacity during periods when the vacuum pump 104 is not connected to the system and is in idle mode. The vacuum storage tank 106 enhances the achievable vacuum level during the process and thus increases production. During the depressurization step, the vacuum pump can be connected to the vacuum storage tank when it is not connected to any column. During the vacuum step, the vacuum storage tank is connected to the column along with the vacuum pump. Tests have shown that using the vacuum storage tank 106 as a reservoir to preserve vacuum capacity improves process efficiency. For example, test results indicate that using a 15cm... 3 -30cm 3 The vacuum storage tank generates an additional 10 std cm 3 / min-20std cm 3 Oxygen per minute.

[0123] In some embodiments, similar to the use of a vacuum storage tank, a pressure buffer can be connected to the pressure pump when the pressure pump is not connected to either column during the vacuum release step. The gas stored by the pressure buffer can be directed into the column during the pressurization step to help increase the process pressure. It is conceivable that in some embodiments (e.g., when the capacity of the pressure pump is significantly smaller than that of the vacuum pump), the use of a pressure buffer can increase the adsorption pressure by recirculating the pressure pump capacity. In some embodiments, the pressure buffer may be 10 cm in size. 3 -20cm 3 In some implementations, as described later, the pressure buffer may be configured to contain an adsorbent, such as zeolite. The vacuum release step typically takes 0.1 to 1.0 seconds, which is the time required for the vacuum pressure to reach ambient pressure by connecting the column to the surrounding environment. Considering the pressure pump capacity, the air delivered during this period is 25 cm³. 3 -250cm 3 The size limitations of portable and / or non-stationary devices mean that it may be advantageous for pressure buffers to incorporate adsorbents to increase the volume of gas stored. If the adsorbent selectively adsorbs N2 (such as Li-LSX zeolite), the system configuration can be modified to supply oxygen to the column and vent waste N2. For example, a valve can be provided to connect the pressure buffer to the ambient environment. This valve can be closed when the pressure buffer is filled by a pressure pump and can remain closed for a period of time after the filling phase, allowing the pressure buffer to supply gas (oxygen-enriched air) to the column, thereby helping to increase the adsorption pressure. As the pressure buffer gradually loses its pressure, the oxygen concentration within it will decrease. When it falls below a predetermined threshold (e.g., about 21%), the pressure buffer can be disconnected from the column, and the valve can open to release the remaining gas (N2-enriched air) to the ambient environment. In this way, the pressure buffer can operate similarly to an adsorbent column. Alternatively, the adsorbent in the pressure buffer can be a material that (e.g., non-selectively) adsorbs both N2 and O2.

[0124] In some embodiments, process gases may be used as coolants, including feed air and exhaust N2. In some embodiments, the feed air and exhaust N2 may be guided by a cooling fan to cool the pump before entering the process or leaving the unit. In some embodiments, the disclosed unit may not include a cooling fan. Depending on the cooling efficiency, a separate fan may or may not be required.

[0125] In some implementations, oxygen canisters can provide oxygen when it may not be otherwise supplied from the column during the process. Oxygen canisters capable of being injected with high-purity product gases (such as oxygen) can be configured with an oxygen canister pressure, for example, between 1.8 bar and 2.5 bar, and a pressure of, for example, 45 cm⁻¹. 3 -60cm 3The size. During testing, it was found that maintaining the oxygen tank pressure slightly above the equilibrium pressure (P... EQ This is beneficial. Specifically, the method retains the high-purity gas contained within the oxygen tank during the equalization process, preventing it from flowing into the column and subsequently being discharged as waste. In some embodiments, there is a transient state during the startup of the oxygen concentrator system, during which the oxygen purity in the product gas slowly increases until it reaches a steady state, e.g., 90% purity, within a typical transient time of 5-10 minutes. Using an oxygen tank during the startup phase can significantly shorten this transient state to 30-60 seconds, or 3-6 cycles. In some embodiments, a vacuum pump 104 can be used to evacuate columns 110, 120 to below atmospheric pressure before shutting down system 100. Tests have shown that evacuating the columns before shutdown improves system efficiency during subsequent startup (e.g., by enhancing residual N2 desorption).

[0126] Consistent with the disclosed implementation, the production gas flow is initiated only when the column pressure exceeds the oxygen tank pressure. There are brief periods within each cycle, such as 0.1 s to 3.0 s, during which the oxygen tank pressure is higher than the column pressure, and therefore no product supply is received from the oxygen concentrator system. If a pulsed oxygen delivery occurs during this period, for example, triggered by a user's breathing, the oxygen tank must be able to maintain the required single-dose volume of 30 cm³. 3 -50cm 3 / breath. If continuous oxygen delivery is required, the oxygen tank must be able to maintain a continuous flow of oxygen during that period. After a single dose volume is withdrawn, the oxygen tank pressure should not drop below the minimum oxygen tank pressure, such as 1.8 bar as disclosed herein. On the other hand, the selection of the oxygen tank volume needs to take into account the size of the portable device.

[0127] In some implementations, pressure equalization can be achieved using product gas from the oxygen tank instead of gas directly from an alternative column. In this way, pressure equalization can be performed via a purge valve ( Figure 1 Equalization is performed using V9 in the system. Equalization using oxygen tank gas and gas from an alternative column achieves a similar effect. This method reduces the number of valves required because the equalization valve can be removed. Figure 1 (V8 in the middle).

[0128] column

[0129] In some implementation schemes, such as Figure 9A and Figure 9BAs shown, columns 110 and 120 can be rounded rectangular shapes with a length-to-hydraulic diameter (L / D) ratio of approximately 3.5. In large-scale adsorption processes, packed bed adsorption columns are typically cylindrical. This is because the cylindrical shape provides a high surface area to volume ratio, allowing for more efficient mass transfer between the adsorbent and the fluid. However, in the case of compact micro-devices (such as the disclosed device), integrating columns with curved surfaces near other components can be challenging. Consequently, using a rounded rectangular column shape better balances the need for efficient mass transfer with compatibility with other components in the micro-device. Furthermore, the column volume can be as small as 95 cm³. 3 Up to 100cm 3 Within a certain range. The column volume can depend largely on the amount of zeolite adsorbent required in each column. The volume is sufficient to contain the required amount of zeolite and other necessary components within the column. Furthermore, the volume can be feasible for portable devices.

[0130] In some implementations, the product end of the column (also referred to as the column closure) has a protruding cylindrical extension that allows the column to be easily inserted into or removed from a corresponding 3D printing socket. In some implementations, an end cap with a groove for an O-ring is used for column closure at the feed end. When the end cap is screwed onto the column, the O-ring is compressed, forming a tight seal. For safe operation of the process, the column needs to be held at least 3.0 bar. End caps can be smaller and lighter than other types of column closures, such as flanges. The above description refers to a column (not shown) with a tube configuration having a feed end on one side and a product end on the other. Figure 9A and Figure 9B The U-shaped column has two protruding cylindrical extensions on one side for feeding (111 / 121) and product (113 / 123), while the column is "closed" on the other side by a grooved end cap.

[0131] The column includes a product-end extension positioned at the center of the column end face to ensure uniform fluid distribution. The diameter is 2mm to 4mm. The diameter of the extension should be maximized to the maximum possible to prevent any restriction on the flow path.

[0132] Figure 9A and Figure 9BExemplary U-shaped dual columns 110 and 120, consistent with the disclosed embodiments, are depicted. Each column includes at least two openings at its top, an inlet and an outlet. The inlets (111, 121) are configured to guide a gas flow into the column, and the outlets (113, 123) are configured to guide an oxygen-enriched gas flow out of the column. Each column also includes a partition (115, 125) configured to separate the columns and guide airflow from one side of the partition to the opposite side through openings (channels or gaps) at the bottom of the partition, reaching the outlet (113, 123). Reference Figure 9A Adjacent columns 110 and 120 may have separate walls 117 and 127, or the two columns may share a single wall.

[0133] Consistent with the disclosed embodiments, U-shaped columns can be used to increase the achievable length-to-diameter (L / D) ratio in portable devices. A higher L / D ratio generally has a negative impact on product production because it can lead to a higher pressure drop across the column. However, in portable devices where the flow is primarily laminar, the column pressure drop is insignificant due to the shorter column length and relatively lower flow rate compared to large-scale processes. In this case, it is suggested that using a column with a higher L / D ratio results in a higher oxygen recovery rate.

[0134] In some implementations, the oxygen concentrator system may be configured to include three or more columns. Each cycle in the oxygen concentrator system has three steps: column feed, pressurization, vacuuming, or connection to ambient pressure (depressurization and / or vacuum release). Having three columns to synchronize with each stage may be advantageous.

[0135] Adsorbent

[0136] In some embodiments, the adsorbent used in the column is zeolite Li-exchange low silica X-type (Li-LSX) zeolite, where the Si to Ai ratio is equal to 1. Li-LSX exhibits high N2 adsorption capacity and high selectivity for N2 relative to O2. It is widely considered a superior option available in the portable oxygen concentrator market. Furthermore, the zeolite particle size ranges from 300 μm to 600 μm. The particle size of the zeolite is selected to ensure sufficient surface area, reasonably compact packing, and ease of manufacture. In some embodiments, the zeolite adsorbent can be sieved via a sieving process before assembly into the column, which improves the uniformity of the zeolite particle size. Using zeolite particles with a narrower size range, as well as larger particles (over 400 μm), can reduce column pressure drop by 15% to 20%, which can have a positive impact on oxygen production.

[0137] In some implementations, the volume of zeolite is in the range of 55 to 65 grams per column, totaling 110 to 130 grams when two columns are present. The choice of zeolite volume is related to several factors: 1) Column size and shape. Sufficient bed length is required to avoid N2 penetration in each cycle. On the other hand, the column size needs to be feasible in a portable device. 2) Pressure and vacuum pump capacity. The zeolite volume per column determines the volume of feed air required to pressurize the column to the desired adsorption pressure, and the volume of exhaust gas required to reach the desired desorption pressure. Zeolite is packed into the column using the following procedure: 1) Zeolite particles are poured in layers while the column is vibrated to ensure uniform distribution; 2) After the column is completely filled, the column is consolidated by tapping the bed to allow the particles to settle. This process was developed to achieve a tight packing of zeolite particles to prevent fluidization of the particles during pressure swing adsorption.

[0138] In some embodiments, the product storage tank 130 and / or the product buffer 510 may comprise zeolite of the same type as that included in the adsorbent column. In some embodiments, the column, product storage tank, and / or product buffer may comprise materials different from each other.

[0139] Besides zeolites, various materials may include one or more of carbon molecular sieves, graphite, activated carbon organic frameworks (COFs), and metal-organic frameworks (MOFs). In some embodiments, columns, product storage tanks, and product buffers may include hydrogen-bonded organic frameworks (HOFs) as adsorbents to generate production gases and increase storage capacity. HOFs are porous polymeric materials that self-assemble via H-bonding between organic linkers. H-bonding can possess unique properties, including weak, flexible, poorly directional, and reversible. These unique properties endow HOFs with unique advantages over materials such as zeolites, MOFs, and COFs, such as ease of solution processing and characterization, simple purification, and the ability to be repaired through recrystallization.

[0140] Additionally, the HOF may exhibit higher selectivity for oxygen than for nitrogen and argon. Consequently, it can be used in a second-stage pressure swing adsorption (PSA) process to further purify the oxygen product. In some embodiments, the HOF is hydrophobic. Therefore, the adsorption capacity of the HOF is unaffected by the moisture present in the room air. Consequently, column replacement and product buffers are unnecessary due to the absence of moisture-induced degradation.

[0141] Bottom manifold and top manifold

[0142] like Figure 10AAs shown, a column-top filter element can be combined with a filter assembly having the same cross-sectional shape as the column, characterized by an integrated mesh structure printed at its center. The pore size of this mesh can be smaller than the zeolite particles used (<200 μm), thus acting as an air barrier to prevent zeolite leakage from the column. The filter assembly has larger pores (2 mm-5 mm) to minimize flow restriction. A small buffer is used at the top of the filter element to minimize pressure drop. In some embodiments, materials as electrostatic and hydrophobic polypropylene (e.g., filter sheets / membranes) can also be used as filters. Ideally, the filter should produce no (or minimal) pressure drop, allowing free airflow and filtering out zeolite. Tests have shown that filter sheets / membranes are the most effective. Advantages of such materials include ease of cutting and placement, as it is a single sheet material, unlike O-ring design filters, where tolerance issues are not a concern. Furthermore, these filter sheets are also used as bite-mouth filters for bacteria / viruses.

[0143] like Figure 10B , Figure 10C and Figure 10D As shown, the bottom filter element can be similar to the top filter element, having a filter assembly with the same cross-sectional shape as the column. The bottom filter element can have a greater wall height; a greater wall height (a taller wall) can suppress tilting of the filter assembly during installation. For example, the filter wall can align the filter element with the inner wall of the column, and a longer wall allows for better alignment and reduces the likelihood of filter tilting and jamming. Furthermore, as... Figure 10C and Figure 10D As shown, a spring can be installed between the column's bottom cap and the bottom filter element. The spring holds the bottom filter in place and applies compressive pressure to the zeolite packed bed to prevent fluidization. The spring's loading height needs to match the distance between the column's bottom cap and the bottom filter element.

[0144] In some implementation schemes, such as Figure 1 As shown, the oxygen concentrator system may include six C15 solenoid valves at the feed end of the column to allow pressurization using pressure pumps (V1 and V4), depressurization (venting) to ambient pressure (V3 and V6), and depressurization using vacuum pumps (V2 and V5). In some embodiments, the oxygen tank and four check valves (CV2, CV3, CV4, and CV5) may be integrated into a single component. This integrated design of the oxygen tank and check valves reduces device size and weight, and minimizes end space void volume. The end space void volume, i.e., the void volume at the feed and product ends of the column, should be minimized to the maximum possible extent. Feed-end space void causes gas to be compressed but not processed by the column, thus reducing oxygen recovery and increasing power consumption. The product-end space void contains product gas that is not delivered to the user and may be discharged when the column pressure decreases.

[0145] In some implementations, the oxygen concentrator system may include multiple control valves, while in other implementations, the number of valves can be reduced by using suitable two-way valves, two-way valves, three-way valves, four-way valves, or rotary valves, and by combining several flow channels. Using fewer valves reduces the size, weight, and power consumption of the portable device.

[0146] Typically, control valves can be of any size. In some exemplary embodiments, the control valve has an orifice size exceeding approximately 1.5 mm. The disclosed handheld oxygen concentrator system operates with rapid cycles (e.g., 5-12 seconds). In some embodiments, pressurization and / or depressurization may require less than 4 seconds to complete. Therefore, it is advantageous to have minimal flow restrictions on the control valve to accommodate higher gas velocities, especially for valves at the column feed end handling larger volumes of gas. Test results indicate that using control valves with larger orifices and / or shorter cycle times is possible and may result in greater oxygen production.

[0147] Consistent with some exemplary disclosed embodiments, the control valve has a response time of less than approximately 10 ms. This rapid response of the control valve results in reduced delay when switching gas directions. Due to the nature of the short cycle time, consistent delays within each cycle accumulate rapidly over time and can potentially disrupt cycle operation.

[0148] In some implementations, the inner diameter of the tubing or connector may exceed about 2 mm. In some applications, a tubing wall thickness greater than about 1 mm can prevent kinking. As previously explained, reduced flow restriction along the flow path can be advantageous. To achieve low restriction, in some implementations, the inner diameter of the tubing / connector may be larger than the size of the control valve orifice. The length of the tubing / connector may also be limited to minimize pressure drop. In some implementations, it may be desirable for both the tubing and the connector to have a circular cross-section. Compared to other shapes, a circular cross-section provides a more uniform flow distribution and better prevents turbulence. Circular tubing / connectors can also be cost-effective because they are readily available on the market. Generally, shorter and wider tubing / connectors may be preferable to longer and narrower parts to reduce flow restriction. The selection of size and length should aim to minimize pressure drop across the tubing / connector.

[0149] Recovery rate is defined as the ratio of product oxygen to feed oxygen, describing the effectiveness of utilizing the feed stream and is an important parameter in the adsorption process. Due to size and maximum adsorption pressure limitations, recovery rates in portable oxygen concentrators are typically 30%–35%. As disclosed herein, the disclosed oxygen concentrator system achieves a recovery rate of 54%.

[0150]

[0151] Another important characteristic of the adsorption process is the bed size factor (BSF), which describes the effectiveness of utilizing the adsorbent (e.g., zeolite). The BSF is defined as the ratio of the weight of the adsorbent to the weight of the product, as shown in the following equation. A smaller BSF indicates more efficient use of the adsorbent.

[0152]

[0153] On an industrial scale, a high-recovery BSF (e.g., a BSF corresponding to 50%–60% oxygen recovery) is typically around 350 lbs / TPDO. During prototype benchtop testing, the disclosed system achieved a BSF of 140 lbs / TPDO and is generally more efficient in terms of feed flow and adsorbent (zeolite). To achieve the same oxygen production as a conventional PSA process, the disclosed oxygen concentrator unit implementation can: 1) use lower adsorption pressures—meaning the column material and connections do not need to have the high pressure ratings required for the PSA process; 2) use lower feed flow rates—meaning the pressure pump can be smaller, lighter, and consumes less power; 3) the adsorbent is exposed to fewer contaminants (primarily moisture and CO2 in the feed air), resulting in a longer column life; and 4) use fewer zeolite particles, meaning smaller columns can be used and the unit can be lighter.

[0154] Pressure buffers with adsorbents and product buffers

[0155] In some embodiments, the disclosed oxygen concentrator includes a pressure buffer and a gas storage tank (e.g., as...). Figure 1 The product storage tank 130 shown is as follows: Figure 5A The product buffer 510 shown may include oxygen adsorbent material to increase the storage capacity of the gas in the tank. In such cases... Figure 1 In the case of the product storage tank 130 shown, the gas entering the buffer is the product gas from the adsorption process (e.g., oxygen of selected purity—87%-95%, etc.). Therefore, any adsorbent material capable of adsorbing oxygen can be provided in tank 130. Typically, the amount of adsorbent in the tank can depend on the application. In some embodiments, the tank (e.g., product storage tank 130) may be filled with adsorbent to maximize gas storage. Non-limiting examples of adsorbents that can be provided in storage tank 130 include: various types of zeolites; LiLSX—a zeolite commonly used in oxygen concentrator columns; LiX; NaX; NaA; other zeolites that adsorb oxygen; metal-organic frameworks that adsorb oxygen; hydrogen-bonded organic frameworks that adsorb oxygen; molecular sieves; activated carbon, silver and copper-based adsorbents, perovskite oxides, polymer membranes, zirconium-based adsorbents, etc.

[0156] Similarly, in such Figure 5AIn the case of the product buffer 510 shown, the gas entering the buffer is the product gas from the adsorption process (e.g., oxygen of selected purity—87%-95%, etc.). Therefore, any adsorbent material capable of adsorbing oxygen can be provided in the product buffer 510. Typically, the amount of adsorbent in the product buffer 510 can depend on the application and can be multiple options for the user during replacement of the removable module 150. In some embodiments, the product buffer 510 may be filled with adsorbent to maximize gas storage. Non-limiting examples of adsorbents that can be provided in the product buffer 510 include: various types of zeolites; LiLSX—a zeolite commonly used in oxygen concentrator columns; LiX; NaX; NaA; other zeolites that adsorb oxygen; metal-organic frameworks that adsorb oxygen; hydrogen-bonded organic frameworks that adsorb oxygen; molecular sieves; activated carbon, silver and copper-based adsorbents, perovskite oxides, polymer membranes, zirconium-based adsorbents, etc.

[0157] It should be noted that the terms "tank," "storage tank," "product storage tank," and "product buffer" are used interchangeably and can be used for the same function and the same design. In some embodiments, the portable oxygen concentrator may include a product buffer only in the body of the portable oxygen concentrator. In some embodiments, the portable oxygen concentrator may include a product buffer both in the body of the portable oxygen concentrator and in a removable module. In some embodiments, the portable oxygen concentrator may include a product buffer only in the removable module. The number and placement of the product buffers can be customized to meet user requirements.

[0158] Since the pressure in the product buffer fluctuates between the highest and lowest buffer pressures (Pb-max and Pb-min), its storage capacity depends on the oxygen adsorption capacity at these two pressures.

[0159] ΔV=(C(P_(b-max))-C(P_(b-min))) m

[0160] Where C(P) is the adsorption capacity at pressure P (in ml / g), m is the mass of adsorbent placed in the product buffer, and ∆V is the buffer storage capacity. In the case of our disclosed process, Pb-max is slightly below the process adsorption pressure Pads (approximately 2.2 bar), and Pb-min is typically slightly below the column pressure at the start of the purging step (approximately 1.8 bar).

[0161] When product storage tank 130 was filled with LiLSX and 5A zeolite during benchtop testing, it was found that the storage capacity of tank 130 was 2 to 2.5 times that of an empty buffer. Due to the increased storage capacity, the same amount of gas storage can be achieved using a much smaller buffer (40% to 50% of its original size). This makes the disclosed oxygen concentrator smaller and lighter. Product storage tank 130 is used to supply product gas to the user when the adsorption process is still close to steady state, or (in the case of pulse delivery) when the process cannot maintain the high flow rate required at that moment. For a fixed-size buffer (e.g., tank 130), the presence of the adsorbent allows for a longer product gas supply period. The cyclic nature of pressure swing adsorption means that the product gas flow rate fluctuates in each cycle. Storage tank 130 smooths the gas delivery and potentially allows for the elimination of electronic valves used to control the product flow rate. The humidity level in the product gas is very low (relative humidity <1%) because the gas has passed through the entire adsorbent column, where moisture has been removed. Therefore, the adsorbent in storage tank 130 experiences minimal contamination over time, which means that minimal tank maintenance or replacement work is required during the life of the oxygen concentrator.

[0162] It should be noted that while the use of adsorbents in gas storage tanks is described in reference to product storage tank 130 (or product buffer 150) for oxygen concentrators, it is not a limitation. Generally, adsorbents can be provided in gas storage tanks used in any application requiring temporary gas storage. Gas storage tanks are widely used in various industries. These tanks are designed to store gases in compressed or liquefied form for later use. Some non-limiting applications in which gas adsorbents can be included in gas storage tanks include: oxygen tanks for healthcare (e.g., to provide supplemental oxygen to patients); industrial gas storage (e.g., storage tanks for storing gases such as nitrogen, hydrogen, helium, and argon used in welding, cutting, and various other industrial processes); LPG tanks, which are commonly used in residential and commercial environments to store propane and butane gases (e.g., for heating, cooking, and powering appliances); cryogenic tanks for storing gases at extremely low temperatures (e.g., liquid nitrogen, liquid oxygen, and liquid hydrogen); underground natural gas storage tanks or caverns that store natural gas for distribution to homes and businesses; and compressed air tanks, which are used for applications requiring... For a variety of applications requiring a consistent source of compressed air (e.g., including pneumatic tools, scuba diving, and industrial processes); hydrogen storage tanks for fuel cell vehicles; acetylene storage tanks; CO2 tanks for various applications (e.g., including beverage carbonation, firefighting, etc.); anhydrous ammonia tanks for storing and transporting ammonia in agriculture (e.g., as fertilizer); gas storage bottles or canisters for storing various specialty gases (e.g., calibration gases for laboratory equipment, etc.); emergency breathing air canisters for providing workers with breathable air in emergency situations; and gas storage tanks for storing propulsion gases, life support gases, and scientific instrument gases in space exploration applications, etc.

[0163] In each of these gas storage tanks, an adsorbent configured to adsorb the gas stored in the tank and suitable for the application may be provided. For example, in an oxygen tank, an adsorbent for adsorbing oxygen (e.g., zeolite, molecular sieve, activated carbon, silver-based adsorbent, copper-based adsorbent) may be provided, and in a nitrogen tank, an adsorbent for adsorbing N2 (e.g., zeolite, molecular sieve, carbon molecular sieve, polymer membrane, metal-organic framework, carbon nanotube, silica gel, etc.) may be provided. In some embodiments, the adsorbent used in the gas storage tank may not alter or affect the composition of the gas stored in the tank. In other words, the composition of the gas entering the tank and the composition of the gas leaving the tank may be substantially the same. The amount of adsorbent provided may depend on the application. In some embodiments, the tank may be filled with adsorbent. In some embodiments, the tank may not be filled with adsorbent. Instead, a smaller amount may be provided (e.g., 25%, 50%, 75%, etc., of the tank volume). The adsorbent in the gas storage tank may increase the amount of gas stored in the tank.

[0164] Exemplary automation process of the disclosed oxygen concentrator

[0165] Furthermore, this application describes an automated process. The automated process generates optimal process parameters and controls operation accordingly. This device and its automation are not limited to oxygen production—they can be applied to automate any gas separation process, given the use of appropriate adsorbents and sensors. The addition of one or more automated algorithms energizes the portable, non-stationary oxygen concentrator system and enables it to be used with greater flexibility to produce different gases at different concentrations and in different applications.

[0166] In some embodiments, the disclosed portable and handheld oxygen concentrators may be configured to receive feed air and exhaust oxygen-enriched air, and may include a user interface, multiple sensors, one or more pumps (e.g., two pumps), at least two adsorbent columns, and a controller. The user interface enables the user to interact and communicate with the portable non-stationary oxygen concentrator. The user interface may be a graphical user interface (GUI), which is an interface through which a user interacts with an electronic device such as a computer and smartphone using icons, menus, and other visual indicators or representations (graphics). The user interface may also include a display screen, keyboard, buttons, mouse, and applications or websites to transmit user interactions wirelessly. Sensors may include at least a temperature sensor, a humidity sensor, a pressure sensor, a product purity sensor, a flow sensor, and other related sensors (e.g., a CO2 sensor). In some embodiments, at least one of these sensors may be a built-in sensor on the body of the portable non-stationary oxygen concentrator. In some embodiments, sensors may not be included in the portable non-stationary oxygen concentrator, particularly sensors for measuring the atmosphere and environment surrounding the portable non-stationary oxygen concentrator, such as temperature sensors, humidity sensors, and CO2 sensors. The portable non-stationary oxygen concentrator may be configured to use a single pump that provides positive pressure flow and vacuum exhaust. In some implementations, a portable non-stationary oxygen concentrator may be configured to use one pump to provide a positive pressure flow and another pump to provide vacuum exhaust.

[0167] In some implementations, the controller is electrically connected to various components of the portable, non-stationary oxygen concentrator, such as multiple valves, multiple sensors, a user interface, and a pump. Methods for operating and monitoring the portable, non-stationary oxygen concentrator can be implemented via programs stored in memory. Figure 11As shown, in some embodiments, controller 800 may include one or more processors 810 operable to execute programs stored in one or more memories 820. The controller may also include one or more GUIs 830 capable of collecting instructions or input from a user or a caregiver and displaying information output by the one or more processors. In some embodiments, the controller may be associated with a non-transitory computer-readable storage medium that may include instructions for controlling the operation of a portable oxygen concentrator. As used herein, a non-transitory computer-readable storage medium (or a similar construct, such as a non-transitory computer-readable medium) refers to any type of physical memory on which information or data readable by at least one processor can be stored. Examples include random access memory (RAM), read-only memory (ROM), volatile memory, non-volatile memory, hard disk drives, CD-ROMs, DVDs, flash drives, magnetic disks, any other optical data storage media, any physical media with patterns of holes, markings, or other readable elements, PROMs, EPROMs, FLASH-EPROMs, or any other flash memory, NVRAMs, caches, registers, any other memory chips or cartridges, and their networking versions. The terms "memory" and "computer-readable storage medium" can refer to multiple structures, such as multiple memories or computer-readable storage media located within a portable oxygen concentrator or at a remote location. Additionally, one or more computer-readable storage media can be used to implement computer-implemented methods. Therefore, the term "computer-readable storage medium" should be understood to include tangible articles and exclude carrier waves and transient signals.

[0168] Computer-readable storage media may contain instructions that, when executed by at least one processor, cause the at least one processor to perform operations including switching valves, monitoring and controlling pumps. The term "at least one processor" can refer to any physical device or group of devices having circuitry that performs logical operations on one or more inputs. For example, at least one processor may include one or more integrated circuits (ICs), including application-specific integrated circuits (ASICs), microchips, microcontrollers, microprocessors, all or part of a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), a field-programmable gate array (FPGA), a server, a virtual server, or other circuitry suitable for executing instructions or performing logical operations. Instructions executed by at least one processor may, for example, be preloaded into memory integrated with or embedded in the controller, or may be stored in a separate memory. Memory may include random access memory (RAM), read-only memory (ROM), hard disk, optical disk, magnetic media, flash memory, other permanent, fixed, or volatile memory, or any other means capable of storing instructions. In some embodiments, at least one processor may include more than one processor. Each processor may have a similar configuration, or processors may have different configurations that are electrically connected or disconnected from each other. For example, processors may be separate circuits or integrated into a single circuit. When using more than one processor, these processors can be configured to operate independently or collaboratively, and can be located in the same location or far apart from each other. The processors can be connected electrically, magnetically, optically, acoustically, mechanically, or through other means that allow them to interact.

[0169] Figure 11 An exemplary flow diagram is depicted for automating a portable, non-stationary oxygen concentrator process to generate improved process parameters, consistent with the disclosed embodiments. In some embodiments, three categories of input data may be present: a first input including user requests, a second input including environmental conditions, and a third input including initialization data provided by the manufacturer. The third input may be configured to start the automation system and may be supplied only once before the automation system begins operation. Other types of input data, such as user requests and environmental data, may be periodically requested, required, and / or provided.

[0170] The automation process can be configured to receive first input data via a user interface from at least one of a user, operator, clinician, or the user's care provider, and from a device that measures the user's health parameters from the user interface. The automation process can also be configured to receive input data from a wired or wirelessly connected external device, which can also be configured to display the user's health parameters, sensor data, and / or the concentrator's performance. In some embodiments, the first input includes one or more of the desired oxygen concentration in the exhaust oxygen-enriched air, the desired flow rate of the exhaust oxygen-enriched air, or the desired exhaust frequency of the oxygen-enriched air. In some embodiments, the first input data can be stored in the memory of a portable, non-stationary oxygen concentrator. The stored first input data can be retrieved later by the controller.

[0171] User requirements may include the desired oxygen concentration input (e.g., 90% oxygen), output flow rate (e.g., 1 standard liter per minute (slpm), or an increasing or decreasing flow rate), and gas delivery frequency (e.g., continuous output, or pulsed output at 5-second intervals). For example, in the case of a portable, non-stationary oxygen concentrator, the user or clinician may state that they require 90% oxygen at 1 slpm, delivered continuously, or delivered in pulses at 5-second intervals.

[0172] The gas volume delivered in each pulse is automatically calculated as the output flow rate divided by the number of pulses per minute. Users can also specify product requirements for different settings, such as 0.5 slpm for user setting 1, 1.0 slpm for user setting 2, and 1.5 slpm for user setting 3. User requirements can be provided at any time the user desires, at specific time intervals, or in response to external changes (e.g., changes in humidity or decreased outside air quality). For example, users can be prompted to reconfirm their requirements weekly.

[0173] Consistent with the disclosed embodiments, the automation process can be configured to receive a second input from one or more sensors of the portable, non-stationary oxygen concentrator. In some embodiments, the second input may include signals indicating one or more of the following: temperature, humidity, pressure, or CO2 level in the feed air, as well as signals from sensors of the surrounding environment.

[0174] In some implementations, portable, non-stationary oxygen concentrators continuously monitor their surrounding environment using multiple built-in sensors, including temperature sensors, humidity sensors, pressure sensors, and other relevant sensors (e.g., CO2 sensors). This data is collected primarily to obtain information about the moisture and CO2 levels present in the feed air. This information is then used to estimate the remaining column life.

[0175] Specifically, ambient temperature can be configured to help predict the real-time adsorbent capacity of the adsorbent material. Adsorption capacity typically decreases at higher temperatures. Ambient pressure can be configured to help predict the performance of pressure pumps and vacuum pumps. While ambient pressure remains relatively consistent during daily activities, it can vary when the user's latitude changes, such as when the user is traveling by plane or hiking. Ambient pressure also varies with weather and cycles daily, with greater daily variation the closer the user is to the equator. The presence of moisture in the feed air is known to contaminate adsorbents, such as zeolites, over time; therefore, obtaining data on the moisture content of the feed air is important. Data on moisture content can be obtained by measuring the relative humidity and temperature of the surrounding environment. Similarly, CO2 in the feed air is known to be a contaminant for adsorbents such as zeolites. Data on the CO2 concentration in the environment can be configured to help predict the remaining lifetime of the adsorbent in the column. Environmental inputs may be required periodically, such as once a day, whenever the unit is turned on (e.g., during initialization), or when external conditions change (e.g., when the weather changes).

[0176] Consistent with the disclosed implementation, the automation process can be configured to receive a third input from preset manufacturer calibration data, including one or more of pressure pump characteristics, vacuum pump characteristics, moisture contamination, oxygen concentration, recovery rate, flow rate, and humidity.

[0177] In some embodiments, preset initial manufacturer calibration data may include information extracted from device datasheets, as well as calibrations for the adsorbent and portable non-stationary oxygen concentrator. In some embodiments, calibration may be performed manually by the manufacturer. In some embodiments, initialization data may be digitally generated in simulations using mathematical modeling and machine learning models. In some embodiments, preset initial manufacturer calibration data may be a one-time input provided in the initial phase. In some embodiments, preset initial manufacturer calibration data may be updated or retrieved by the device at any time. In some embodiments, preset initial manufacturer calibration data may be provided at any other time as required by the device or upon user request.

[0178] The controller may be configured to receive at least one of first input data and second input data on a display, and to determine one or more of the remaining capacity of at least two adsorbent columns and the estimated remaining operating time of at least two adsorbent columns. The display may be a screen, panel, monitor, television, or interface. Consistent with the disclosed embodiments, the controller may receive the first input data from user input or retrieve the first input data from memory. The controller may be configured to receive the second input data from sensors on a portable, non-stationary oxygen concentrator. In some embodiments, the controller may be configured to obtain the second input data based on average sensor data measured from past time periods, such as one day, one week, two weeks, or one month.

[0179] Consistent with the disclosed embodiments, the portable non-stationary oxygen concentrator can receive a first input from a user or user caregiver via a user interface, including one or more of the desired oxygen concentration in the exhaust oxygen-enriched air, the desired flow rate of the exhaust oxygen-enriched air, and the desired exhaust frequency of the oxygen-enriched air. Configured to combine with other data, such as one or more of sensor data and initial manufacturer calibration data, the portable non-stationary oxygen concentrator can display one or more of the remaining capacity of at least two adsorbent columns and the estimated remaining runtime as a first output. In some embodiments, the user or user caregiver can adjust the first input data via the user interface to obtain the desired remaining capacity or estimated remaining runtime of at least two adsorbent columns.

[0180] The second output enables automatic real-time adjustment of portable, non-stationary oxygen concentrators. It can be used to adjust parameters, such as to reduce or eliminate any deviations from desired values ​​of process variables and yield under given operating conditions. Operating conditions may include pump operation, vacuum operation, and switching of multiple valves on or off. Specifically, they may include multiple parameters such as adsorption pressure, desorption pressure, step time, oxygen concentration, and flow rate. Given operating conditions may, for example, refer to maintaining desired or predetermined adsorption and desorption pressures. In some embodiments, given operating conditions may refer to the desired oxygen concentration in the discharged oxygen-enriched air, the desired flow rate of the discharged oxygen-enriched air, or the desired discharge frequency of the oxygen-enriched air, input by the user through a user interface. The third output enables automated process design, allowing configuration to generate optimal operating parameters upon receiving updated user requirements.

[0181] The output parameters can be used to operate the portable non-stationary oxygen concentrator. Sensor data obtained from the portable non-stationary oxygen concentrator, including pressure, flow rate, product purity, etc., can be provided to the algorithm as real-time feedback. Column life monitoring (CLM) tests can be performed periodically to measure adsorbent contamination levels and can form part of the feedback data that allows the control algorithm to adjust oxygen output.

[0182] Figure 12 The pressure pump characteristic curve (f) of the pressure pump is plotted. P (This information can be obtained from the datasheets of the pressure pump manufacturer.) Figure 12 This demonstrates the correlation between downstream pressure and the flow rate that can be delivered by a pressure pump.

[0183] Figure 13 The vacuum pump characteristic curve (f) illustrates the characteristics of the vacuum pump. V (This information can be obtained from the datasheets of vacuum pump manufacturers.) Figure 13 This demonstrates the correlation between upstream pressure and the flow rate that the vacuum pump can extract from the process.

[0184] Figure 14 The correlations (f) with water pollution consistent with the disclosed implementation scheme were depicted. m To understand the relationship between moisture concentration in adsorbents (such as zeolites) and their absorption capacity, a series of calibration experiments can be conducted in which a pair of fresh columns are gradually artificially contaminated with moisture present in the feed air. Column lifetime monitoring (CLM) tests are then performed on the columns under various contamination conditions.

[0185] Figure 14 This illustrates the correlation (Vt) between the concentration of water accumulated in the adsorbent and the volume of feed air entering the column during column lifetime monitoring tests. CLM Lower V CLM This indicates a higher level of contamination, meaning more moisture accumulates in the adsorbent. The moisture content corresponding to the minimum threshold product purity for user settings 1, 2, and 3 is also shown.

[0186] In some implementations, it is preferable to obtain a moisture concentration corresponding to the minimum acceptable product purity at a set product flow rate. For example, assuming the process operates at a constant product flow rate, the product purity gradually decreases as the level of moisture contamination increases. When the product purity (y) O2-PD When the minimum threshold set by the user or clinician is reached, the corresponding V* should be recorded. CLM and x* m ,like Figure 14 As shown.

[0187] The column capacity can be set arbitrarily, similar to battery capacity. For example, if setting 3 is the highest setting, then V* CLM-S3 It can be set to represent 100% capacity, and V* CLM-S1 It can be set to represent 0% capacity. Column life can be reported as a percentage of remaining contamination, serving as an indicator independent of operating conditions.

[0188] Figure 15 Examples with V CLM The correlation (f) of the impact on product purity CLM Specifically, this can be achieved at a fixed product flow rate (for setting 1 to F). PD-S1 For setting 2 to F PD-S2 For setting 3 to F PD-S3 The correlation between product purity and the volume of gas entering the column during CLM testing is set for pre-calibration. V corresponding to the minimum threshold product purity for settings 1, 2, and 3 is also shown. CLM Portable non-stationary oxygen concentrators operate at a constant product flow rate under baseline conditions, such as F... PD-S1 (Setting 1), F PD-S2 (Setting 2) and FPD-S3 (Setting 3). Product purity (y) in these tests O2-PD ) and V CLM Related, because the oxygen concentration at a fixed product flow rate varies with V. CLM Decrease, its correlation is Figure 15 As shown in the image.

[0189] The minimum threshold for product purity can be preset via default settings or user input. For example, in the case of a portable oxygen concentrator, clinicians can specify that the column should be replaced once the product oxygen purity drops below 70%. Figure 15 The curve in the curve obtains the corresponding V under the baseline conditions (settings 1, 2, and 3). CLM As V* CLM-s1 V* CLM-s2 and V* CLM-s3 .like Figure 14 As shown, these values ​​correspond to the maximum permissible water concentration that can accumulate in an adsorbent (such as zeolite), denoted as x*. m-S1 、x* m-S2 and x* m-S3 .

[0190] Figure 16 The effect of pressure on product recovery (f) is illustrated by demonstrating the pre-calibrated correlation between product recovery and the ratio of adsorption pressure to desorption pressure at a fixed oxygen concentration. R The maximum recovery rate corresponding to the maximum pressure ratio is also shown. Process pressure is limited by the equipment in use. For example, the maximum adsorption pressure cannot exceed the pressure rating of the column / pipe / connector, and the minimum desorption pressure needs to be within the operating pressure range of the vacuum pump.

[0191] In some implementations, the controller can be configured to determine the optimal purge volume based on the desorption pressure.

[0192] Figure 17 The effect of desorption pressure on optimal purge volume is illustrated by showing the pre-calibrated correlation between optimal purge volume and desorption pressure (f). PG As the desorption pressure decreases, the optimal purge volume decreases. The optimal purge volume can also depend on the column fouling level, which is determined by V. CLM express.

[0193] Flow rate is calculated based on pressure difference and valve CV.

[0194] F = f F (ΔP,C V (Equation 1)

[0195] The absolute humidity of the air is determined by the measured temperature and relative humidity (f). RH )calculate

[0196] y m = f RH (T,RH) (Equation 2)

[0197] Consistent with the disclosed implementation, the three functions corresponding to the automation of the three sets of output parameters can be used in different contexts, which may include real-time column life monitoring, automatic real-time adjustment, and automatic process design.

[0198] Real-time column life monitoring

[0199] In some embodiments, the controller may be configured to determine the remaining capacity of at least two adsorbent columns based on the volume of feed gas entering at least two adsorbent columns. In some embodiments, the controller may be configured to determine the estimated remaining operating time of at least two adsorbent columns based on the remaining column capacity and the operating conditions of at least two adsorbent columns. This can also be achieved by measuring the time required for the columns to fill to a predetermined pressure. In this way, a built-in flow sensor is not required. The controller is able to calculate V(CLM) using the measured filling time and pressure pump characterization curve (which determines the feed). Details of the CLM test are described elsewhere in this disclosure.

[0200] Two indicators for real-time column lifetime monitoring are proposed to report the remaining lifetime of the adsorbent in the column: remaining capacity and remaining runtime. For example... Figure 14 As shown, the column's working capacity can be set arbitrarily. The real-time volume V of the measured feed gas... CLM Falling on V CLM -max and V CLM-min Between these values, they correspond to 0% and 100% capacity, respectively. Remaining capacity (RC) can be reported to the user as follows:

[0201] (Equation 5)

[0202] The remaining capacity can be converted into remaining operating time based on the moisture concentration accumulated in the adsorbent (such as zeolite). Figure 14 Measured V CLM Indicates the corresponding moisture concentration x m :

[0203] X m = f m -1 (V CLM (Equation 6)

[0204] The corresponding water concentration x m With x* m-s1 、x* m-s2 and x* m-s3A comparison was made to determine the remaining run time of the adsorbent in the column before the moisture concentration reaches its maximum allowable value. x* m-sN (N=Settings) Via V* CLM It is obtained from the following equation:

[0205] (Equation 7)

[0206] The remaining runtime can then be reported in at least three ways, such as based on average operating conditions, based on real-time operating conditions, and based on the time interval between two consecutive CLM tests.

[0207] In some implementations, the controller may be configured to further determine the remaining runtime based on measurements of one or more of relative humidity, temperature, feed flow rate, and production flow rate.

[0208] Average operating conditions include, but are not limited to, ambient relative humidity (RH) and temperature (T), which can be measured by humidity and temperature sensors. Average environmental conditions during previous operation can be used to calculate the average absolute humidity according to Equation 2. (Moisture concentration in the air):

[0209] (Equation 8)

[0210] Consistent with the disclosed implementation, data on previously operated parameters, such as average feed rate, can be stored. And the production flow rate is F PD-SN The most common settings (N=1, 2, or 3, or other settings) are used to calculate average operating conditions. The concentration of water accumulated in the adsorbent during time t is:

[0211] (Equation 9)

[0212] Therefore, the time before the adsorbent in the column reaches the maximum allowable moisture concentration is:

[0213] (Equation 10)

[0214] (N=1, 2, or 3 is the most commonly used setting)

[0215] In some implementations, the remaining runtime can be obtained by using real-time measurements.

[0216] (Equation 11)

[0217] (N = the currently used settings)

[0218] Consistent with the disclosed implementation scheme, the remaining lifetime of the adsorbent in the column is given by combining Equations 2, 6-8, and 10-11:

[0219] (Equation 12)

[0220] In equation 12, f m f CLM f RH It is a pre-determined correlation; y* O2-PD Indicates the minimum oxygen purity threshold (for setting N), set by default or user input; V CLM Measured in CLM testing; F 进料 T and RH are the feed flow rate, ambient air temperature, and relative humidity, respectively, as average values ​​from previous operations or as real-time measurements.

[0221] The remaining runtime can be obtained using the time interval between two consecutive CLM tests. In some implementations, the column is gradually contaminated at a roughly linear rate, corresponding to the amount of time elapsed. The device records the time taken for the previous and current CLM tests. The time elapsed between these two tests is recorded as t. 间隔 .

[0222] (Equation 13)

[0223] Automatic real-time adjustment

[0224] Automatic real-time adjustment capabilities can include elements such as automatic adjustment of process operations and automatic adjustment of product flow. Automatic real-time adjustment can be used to reduce deviations from the unit's initially intended operating conditions caused by moisture contamination of the adsorbent column. As a result, automatic real-time adjustment can continuously operate in the background, providing updated V whenever CLM testing is performed. CLM Automatic adjustment is performed when the value is reached.

[0225] Automatic real-time adjustment is useful because the column can become increasingly contaminated with moisture, reducing the adsorption capacity of the adsorbent within the column. Due to contamination, the expected real-time adsorption pressure (P0.05) will decrease. ads The adsorption pressure is higher than the target adsorption pressure, and the expected real-time desorption pressure (P) is higher than the target adsorption pressure. ads The adsorption capacity is lower. For example, a reduced adsorption capacity can lead to increased column and buffer pressures, which increases the output flow rate and reduces output purity (because the column lacks the capacity to maintain a higher output rate). The target adsorption pressure can be achieved by adjusting the cycle time to be lower.

[0226] In some embodiments, the disclosed oxygen concentrator may not have passive control features due to size and weight limitations required to maintain its portability. Portable devices may be sensitive to minute changes in operating parameters. For example, higher P... ads This may result in a lower feed air velocity delivered by the pressure pump; oxygen recovery may increase due to higher adsorption pressure and lower desorption pressure; purge volume may increase due to the larger pressure difference between the two columns, which may lead to waste of product gas; and the production flow rate via pulse delivery may also increase when the oxygen tank pressure increases, thus reducing the oxygen concentration.

[0227] Variations in the absorption or desorption pressures of disclosed oxygen concentrators can lead to deviations from their initially intended operating parameters. In the case of moisture contamination, existing commercially available oxygen concentrator units largely ignore such deviations. No known commercial unit adjusts the production of oxygen or other gases (or indicates the need for adsorbent replacement) based on the level of adsorbent contamination. The usual practice is to present users with general statements (e.g., "Replace the column every 3-6 months"). To address this issue, some disclosed embodiments use real-time automatic adjustment to keep operating conditions as close as possible to the initial design. In some embodiments, the controller may be configured to determine the real-time adsorption and desorption pressures based on the remaining capacity and predetermined pressure of at least two adsorbent columns (e.g., using a feedback loop).

[0228] Specifically, the cycle time can be adjusted to maintain the required P. ads and P des There is a roughly linear correlation between the gas volume required to pressurize the column to a specific pressure and the pressure itself. This is because the pressure required to pressurize the column to P was measured in the CLM test. CLM V required CLM Therefore, the required volume of feed gas in each cycle is:

[0229] (Equation 14)

[0230] In Equation 14, due to process configuration, P EQ Approximately P ads Half of it.

[0231] Based on the characterization of pressure pumps ( Figure 12 The following equation exists:

[0232] (Equation 15)

[0233] In equation 15, t P This is the stage time of the pressurization / vacuum step. At t=0, P(t)=P EQ ; at t=t PAt that time, P(t) = P ads Combining equations 14 and 15 produces the following equation:

[0234] (Equation 16)

[0235] The same method can be applied to the vacuum side to produce these equations:

[0236] (Equation 17)

[0237] (Equation 18)

[0238] At t=0, P(t)=0; at the end of the vacuum step, t=t V At that time, P(t) = P des Combining equations 17 and 18 yields these equations:

[0239] (Equation 19)

[0240] Real-time adsorption pressure P ads and P des According to V CLM and pressurization / vacuum step time (t) P and t V ) calculation. Due to column contamination, P is expected to be... ads Above the target adsorption pressure, and P is expected to be des Lower. In this case, it will affect t. P and t V Both are applied with a 0.1-second interval reduction, and then the real-time P is recalculated. ads and P des This process will be repeated until the predicted real-time P is achieved. ads and P des Consistent with the target adsorption / desorption pressure, which should be within a certain range (e.g., 2.5 ± 0.1 bar and 0.5 ± 0.05 bar) to allow for some tolerances.

[0241] Figure 18 The pressurization / vacuum step time (t) was described. P and t V The iterative process involves updating the pressurization / vacuum step time. Once the pressurization / vacuum step time is updated, the timing of other steps can remain the same as the design value.

[0242] As the adsorbent column becomes increasingly contaminated with moisture, its adsorption capacity decreases, which is reflected in a reduction in the output product flow rate and / or purity. In portable, non-stationary oxygen concentrators, the output product flow rate and its purity are negatively correlated. Figure 15 Another way to illustrate the correlation between product flow rate and purity is by plotting, such as... Figure 19As shown, it illustrates the relationship between oxygen concentration and V at a constant product flow rate. CLM The pre-calibration correlation between them. Under given operating conditions, a higher output flow rate corresponds to lower product purity, and vice versa. When the column experiences contamination, Figure 19 The curve gradually moves downwards.

[0243] When output flow rate and oxygen concentration change, users can choose to prioritize either flow rate or purity as the more important parameter, which can be kept constant during automatic adjustment to allow the other parameter to decrease when the column becomes contaminated. In this way, the decrease in column capacity is only reflected in the less important parameter.

[0244] In some implementations, if product flow rate is considered more important, it is kept constant in real-time automatic adjustments. In this case, the production valve opening time remains at the initially expected value. Because the adsorption pressure is adjusted to remain the same as the design value, the output product flow rate F* PD Also remain the same. When the column is contaminated, the oxygen concentration is allowed to decrease, which in Figure 19 The purity is displayed by moving from blue hollow data points to orange hollow data points. Real-time purity is reflected in the following equation:

[0245] (Equation 20)

[0246] In some implementations, if oxygen concentration is considered more important, the flow rate can be reduced to maintain the required purity. Figure 19 In the diagram, the decrease is indicated by moving from a blue hollow data point to an orange solid data point. The real-time product flow rate is reflected in the following equation:

[0247] (Equation 21)

[0248] To achieve this flow rate, the production valve opening time t needs to be adjusted accordingly. 脉冲 .

[0249] (Equation 22)

[0250] In Equation 22, f is the product delivery frequency, which can be set by the user as a default value or determined based on a real-time user profile (e.g., data representing breathing patterns); and C v-脉冲 This is the Cv of the production valve. Combining equations 21 and 22 gives the updated pulse time in the equations:

[0251] (Equation 23)

[0252] If the user requires a continuous output flow, the production valve C can be adjusted. VTo achieve the desired output flow rate under the same adsorption pressure.

[0253] Automated process design

[0254] The automated process design function is configured to activate upon receiving a new set of user requirements. When setting new targets for production flow rate / purity, the process operating conditions need to be redesigned accordingly. The control algorithm selects the optimal adsorption and desorption pressures and generates a set of cycle timing sequences. These time sequences are used to operate the portable, non-stationary oxygen concentrator, while internal measurements provide feedback to the algorithm, allowing for fine-tuning of operating parameters.

[0255] In some implementations, automated process design can generate operating parameters for the highest setting from product requirements specified by the user for different settings. Automated process design can provide lower settings by reducing pump speed. The objectives of automated process design may include, in order: 1) achieving the user-specified oxygen concentration and flow rate; 2) minimizing power consumption as much as possible; and 3) minimizing adsorbent contamination as much as possible.

[0256] Users can be offered the option to redefine the priority order of the aforementioned objectives. Once the automated process design is complete, users have the option to manually specify specific operating parameters and override the settings generated by the algorithm. However, the purpose of automating portable, non-stationary oxygen concentrators is to eliminate the time and cost for users to select and set each operating parameter. Therefore, while user overriding is available, it is not expected to become a routine step in the automation process.

[0257] While not strictly necessary, the automated portable non-stationary oxygen concentrator design was developed based on the following test findings of the disclosed portable non-stationary oxygen concentrators: 1) The optimal step sequence is generally similar across various portable non-stationary oxygen concentrators. Therefore, it is proposed to maintain the same step sequence in the automated process design. The operating parameters generated by the algorithm will primarily be the time for each step in the cyclic operation. 2) The optimal step sequence can be determined based on a given adsorption pressure (P). ads ) and desorption pressure (P) des 3) The pressurization / vacuum time was calculated in accordance with the disclosed implementation scheme. The optimal purge volume depends on the desorption pressure (P). des This can be achieved through different combinations of purge flow rate and purge time. The purge effect is independent of the flow rate or time as a single parameter. 4) The optimal equilibrium time depends on the adsorption pressure (P). ads ) and desorption pressure (P) des The difference between 0.3 and 0.5 seconds is sufficient in most cases, and the impact of balancing time is limited within this range. 5) Higher P ads This results in higher oxygen tank pressure (P).ot Therefore, the pulse flow rate controlled by the pressure difference between the oxygen tank and the environment also increases.

[0258] Automatic portable non-stationary oxygen concentrators are designed based on user requirements for product flow rate (F). PD ) and purity (y O2-PD The requirements begin with the adsorption pressure and the ratio of adsorption pressure to product recovery rate. Figure 16 The maximum P that can be mechanically maintained by this process can be determined. ads / P des The maximum recovery rate (R) is determined by user requirements for product purity. max ).

[0259] Assuming the highest adsorption pressure (P) is used in this process 0 ads ) and minimum desorption pressure (P 0 des Then it can be done in P 0 ads The feed flow rate and corresponding P of the lower conveyor 0 EQ Calculated based on the characteristics of the pressure pump ( Figure 12 ), as measured by these equations:

[0260] F Pads = f P (P ads (Equation 24)

[0261] (Equation 25)

[0262] The average feed air velocity can be estimated as F ads and F EQ The average value, as measured by this equation:

[0263] (Equation 26)

[0264] The maximum product flow rate at the required oxygen concentration is measured by this equation:

[0265] (Equation 27)

[0266] If F is calculated in equation 27 PD If the user's requirement is less than the product flow rate, then before recalculating equations 24-27, P ads This will reduce the pressure by 0.05 bar, and P des This will increase by 0.05 bar. Repeat this process until the calculated F... PD Higher than or equal to the required value.

[0267] In some implementations, the controller can be configured to determine the pressurization step time and vacuum step time based on real-time adsorption pressure and real-time desorption pressure.

[0268] Figure 20 The adsorption pressure (P) was described. ads ) and desorption pressure (P) des The iterative process of P. ads and P des This generates the following cyclic sequence: 1) As discussed above in Equations 16 and 19, calculate the pressurization step time t. P and vacuum step time t V ;2) Calculate the purging step time t PG 3) Set the equalization time t EQ ; and 4) Calculate the pulse production time t 脉冲 .

[0269] Purging step time t PG This can be obtained through the following steps. Using the following equation, based on... Figure 18 The predetermined correlation is used to find the optimal purge volume:

[0270] (Equation 28)

[0271] The purge velocity can be calculated using Equation 1 and the following equations based on the pressure difference and the size of the control valve or orifice:

[0272] F PG = f F ((P ads - P des ), C V-PG (Equation 29)

[0273] In equation 29, C v-PG This refers to the purge valve / orifice characteristics. Combining Equations 28 and 29, the purge step time is given by the following equation:

[0274] (Equation 30)

[0275] Equilibrium time t EQ It can be set to 0.4 seconds because when t EQ Its impact is limited within the range of 0.3 to 0.5 seconds.

[0276] The pulse flow rate can be calculated using the pulse valve / orifice characteristics via Equation 1. Similar to Equation 22, and using the following equation:

[0277] F 脉冲 = f F (P ads Cv-脉冲 (Equation 31)

[0278] The pulse time is calculated using the following equation:

[0279] (Equation 32)

[0280] If the user requires continuous output, the production valve Cv can be adjusted to achieve the desired output flow rate.

[0281] After generating the time for each sequential step, the process is run for 10-20 cycles accordingly, and adsorption pressure, desorption pressure, product flow rate, and purity are measured. Except for the pulse time t... 脉冲 In addition, fine-tune the timing of other steps at 0.1-second intervals until the measured parameters fall within the desired range. Pulse time t 脉冲 It can be adjusted in 0.01-second intervals until the desired product flow rate and purity are achieved.

[0282] feedback

[0283] The closed-loop control system may include two types of feedback. The controller is configured to include a closed-loop control system based on continuous sensor data of one or more of the following: adsorbent column fouling level obtained from periodic column lifetime monitoring (CLM) tests, oxygen concentration, production flow rate, temperature, adsorption pressure, and desorption pressure.

[0284] CLM testing can be configured to provide real-time information on the adsorbent column contamination level, forming the basis for real-time control of the portable non-stationary oxygen concentrator and oxygen output. CLM testing should be performed periodically, such as weekly, each time the unit is turned on, or each time the first input data is received. It is worth noting that, unlike sensor data, CLM results may not be available during operation of the portable non-stationary oxygen concentrator. This may be due to the need for both a pressure pump and the adsorbent column for CLM testing, preventing them from being used simultaneously for process operation.

[0285] In the CLM test, with the column product end closed, the two columns are sequentially pressurized to a predetermined pressure (P) using feed gas from the surrounding environment. CLM An online pressure sensor measures column pressure, and when the pressure reaches P... CLM A signal is sent to the control board to stop the pump. An internal timer measures the time (t) taken to complete the test. CLM ).

[0286] The volume (V) of feed gas entering the column during CLM CLM It can be obtained from any of the following:

[0287] 1) Online flow sensor; or

[0288] (Equation 3)

[0289] 2) Based on such Figure 12 The pressure pump characteristic curve shown is calculated. At any given time during CLM, the flow rate delivered by the pressure pump can be determined based on the measured column pressure.

[0290] (Equation 4)

[0291] Continuous sensor data can be a type of feedback in a closed-loop control system. The control algorithm generates output parameters for operating the portable non-stationary oxygen concentrator. Built-in sensors measure process variables in real time, and these measurements can be provided as feedback to the control algorithm, allowing for fine-tuning of the output parameters. Sensor data from the portable non-stationary oxygen concentrator may include, but is not limited to, oxygen concentration (product purity), product gas flow rate, process pressure at various locations within the portable non-stationary oxygen concentrator (such as the feed and product ends of the column), and process temperature at various locations within the portable non-stationary oxygen concentrator, such as data from thermocouples integrated inside the adsorbent column to measure localized adsorbent temperature.

[0292] Valve and pump control

[0293] Consistent with the disclosed implementation, the control algorithm outputs a set of operating parameters, including adsorption pressure, desorption pressure, cycle time, step time, optimal purging (volume, time, flow rate), product delivery (flow rate, frequency), pump capacity (e.g., operating at 50% full capacity), etc. The operation of the portable non-stationary oxygen concentrator (which includes controlling pump operation, vacuum operation, and switching of multiple valves open or closed using a set of operating parameters determined by the control algorithm) can be translated into a set of instructions for controlling each valve and each pump in the portable non-stationary oxygen concentrator. As an example, the instructions might look like this:

[0294]

[0295] The portable, non-stationary oxygen concentrator can operate according to this set of instructions. Then, built-in sensors collect multiple real-time measurements from the portable, non-stationary oxygen concentrator as feedback information, as discussed in this paper.

[0296] Some embodiments of an oxygen concentrator may include a single pressure sensor, while other embodiments may include multiple pressure sensors. For example, a single pressure sensor may be integrated into a buffer tank (e.g., oxygen storage tank 130) and this single pressure sensor may monitor the pressure of both columns 110, 120, and cut off or stop pressurization when the adsorption pressure in the column is reached. Alternatively, a single vacuum pressure sensor may be integrated into a vacuum line, where it monitors the desorption pressure of both columns 110, 120, and cuts off or stops pressurization / vacuum when a target desorption pressure in the column is reached. However, in some embodiments, a single pressure sensor may not be able to pick up the vacuum pressure of both columns; in some embodiments, a single vacuum pressure sensor may not be able to pick up the positive pressure of both columns. Therefore, in some embodiments, a single pressure sensor configuration may not be able to determine when the column has fully reached the adsorption or desorption pressure. In some embodiments, for more accurate monitoring, the device may include multiple pressure sensors. For example, in a dual-column device (e.g., Figure 1 As illustrated, the device may include two pressure sensors to individually measure the pressure of the two columns. Since the two pressure sensors can detect the absolute pressure of the two columns, they will also detect the adsorption and desorption pressures of the columns (which indicate the degree of “cleanliness” of the columns at the end of the desorption process).

[0297] When pressurization is terminated after adsorption pressure is reached in a column, the adsorbents in the two columns may initially have different lifetime (contamination) states. Dynamic sequence timing, which allows the two columns to operate with different cycle times, is considered the best method for handling imbalances between the two columns. In a dynamic timing setup, the cycle time is adjusted according to the column undergoing the adsorption phase; this means that the cycle time is longer when the less contaminated column is experiencing adsorption, and shorter when the more contaminated column is experiencing adsorption. When pressurizing the column with more contaminated adsorbent, adsorption pressure can be reached more quickly with shorter cycle times. In other words, the less contaminated column may not have enough time to reach the target desorption pressure. This means the "better" column cannot achieve a full pressure swing, resulting in reduced recovery. Consequently, oxygen purity may decrease during production from the less contaminated column. However, returning from the weaker desorption pressure to the adsorption pressure may require less feed air, and the longer cycle time due to the increased N2 capacity may mitigate the contamination / aging effects on the less contaminated column. When the column is pressurized, columns with heavier adsorbent contamination may have ample time to reach the desorption pressure and thus may begin in a "fresher" state. In some cases, more feed air may be required, accelerating aging. In other cases, lower sub-atmospheric pressure conditions may also "reverse" aging. Fresher adsorbents (such as zeolites), with their increased pressure swing range (from their lower desorption pressure), can provide better recovery rates, thus offering better output purity.

[0298] Including a single sensor or multiple decoupled sensors in each column 110, 120 also enables the device to operate with different parameter sets in each column, such as with dynamic sequence timing. In other words, columns 110, 120 do not need to operate with the same parameter set or at the same timing. Instead, they can operate with mismatched timing to achieve maximum output. The benefit of operating different parameter sets on different columns is that the columns can operate at different stages of their lifespan—because one column may be more contaminated (contaminated with water) than another—to achieve maximum output and maximize column lifespan.

[0299] The foregoing description has been presented for illustrative purposes. It is not exhaustive and is not limited to the precise form or implementation disclosed. Modifications and adaptations to the disclosed implementation will be readily apparent in light of the specification and practice of the disclosed embodiments. For example, the specific implementations described include hardware, but systems and methods consistent with this disclosure can be implemented in both hardware and software. Furthermore, while certain components have been described as interconnected, such components may be integrated with each other or distributed in any suitable manner.

[0300] Furthermore, while exemplary embodiments have been described herein, the scope includes any and all embodiments having equivalent elements, modifications, omissions, combinations (e.g., across aspects of various embodiments), and adaptations or alterations based on this disclosure. Elements in the claims will be interpreted broadly based on the language used in the claims, and not limited to the examples described in this specification or during the examination of this application, which will be interpreted as non-exclusive. Moreover, the steps of the disclosed method may be modified in any way, including reordering steps or inserting or deleting steps.

[0301] The features and advantages of this disclosure are apparent from the detailed description, and therefore the appended claims are intended to cover all systems and methods falling within the true spirit and scope of this disclosure. As used herein, the indefinite articles “a” and “an” mean “one or more”. Similarly, the use of plural terms does not necessarily indicate a plural number unless explicitly indicated in the given context. Furthermore, since many modifications and variations will readily occur upon studying this disclosure, it is not intended to limit this disclosure to the exact constructions and operations illustrated and described, and therefore all suitable modifications and equivalents may be invoked within the scope of this disclosure.

[0302] As used herein, unless otherwise specifically stated, the term "or" covers all possible combinations, unless impractical. For example, if a statement component may include A or B, then unless otherwise specifically stated or impractical, the component may include A, or B, or A and B. As a second example, if a statement component may include A, B, or C, then unless otherwise specifically stated or impractical, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C.

[0303] It should be emphasized that the above description is merely exemplary, and many variations and modifications are possible. For example, in some embodiments, the outputs of multiple (2, 3, 4, 5, etc.) of the disclosed oxygen concentrators can be fluidly coupled together to amplify the produced product gas. In some embodiments, a "T-connector" can be used to daisy-chain multiple oxygen concentrators together and deliver the combined product gas to, for example, a user or storage tank. In some embodiments, multiple oxygen concentrators can be combined with a battery holder and sensors / software configured to detect and synchronize the connected devices. In some such embodiments, multiple oxygen concentrators can be connected to a battery holder and pushed by a trolley to allow for flexible scaling.

[0304] In some disclosed oxygen concentrators, purging and equalization can be performed upstream of the buffer, for example, to prevent unwanted fluctuations in the product flow rate.

[0305] In some implementations, the columns can be reset when the device is shut down. For example, sufficient time can be provided before shutting down the disclosed oxygen concentrator to allow the vacuum pump to reduce the pressure of both columns to a maximum level (e.g., 0.3 bar), after which the system can be shut down to allow complete desorption.

[0306] In some implementations, biocompatible filter materials (e.g., readily available biocompatible filter materials) can be used in the zeolite column.

[0307] In some implementations, the cycle time of the disclosed oxygen concentrator can be adjusted to match the user's breathing profile. For example, the cycle time can be automatically adjusted to match the user's breathing profile (detected by a breathing sensor or pre-loaded by a clinician for a specific disease type), so that the peak production flow rate coincides with the user's inhalation. In such methods, a smaller volume product storage tank can be used.

[0308] In some implementations, the zeolite column can be circulated with hot air to dry the zeolite and maximize output and column life.

[0309] In some embodiments, the disclosed oxygen concentrator may include a desiccant column housed within a secondary column. This secondary column may be regenerated separately by introducing, for example, hot air to dry the desiccant, or may be removed from the oxygen concentrator or regenerated / maintained.

[0310] In some embodiments, the disclosed oxygen generator may be configured with a flight / high-altitude mode. For example, a pressure sensor may calibrate the oxygen output to compensate for lower cabin pressure or FiO2 at high altitudes. In some embodiments, the pressure sensor may be integrated into the device. In some embodiments, the disclosed oxygen concentrator may be equipped with a transceiver and may be configured to wirelessly transmit and receive data (e.g., transmit operating parameters and performance metrics to an external controller, receive instructions to change operating parameters, etc.). In some such embodiments, the pressure sensor may be an external sensor (e.g., wirelessly transmitting signals to the oxygen concentrator).

[0311] In some embodiments, the disclosed oxygen generator can be attached to or integrated with a high-flow-rate (e.g., flow rate range of 2 L / min–60 L / min) nasal therapy device, such as a humidifier with an integrated flow generator that delivers high-flow-rate, warmed and humidified breathing gas to a spontaneously breathing patient. The addition of the disclosed oxygen concentrator provides a portable device that instantaneously generates oxygen and offers portability, versatility, and continuity of care.

[0312] In some embodiments, the disclosed oxygen concentrator can be configured as a sports training device. For example, the disclosed oxygen concentrator can be configured as a sports training aid to create a low-oxygen FiO2 environment of 15% and simulate high-altitude training. The oxygen separated from the gas flow during the adsorption process can be discarded, while the adsorbed N2 is released to the user (N2 - concentrated gas). In some embodiments, such a device can be configured as a bedside device (e.g., a larger device) with a greater emphasis on quieter operation (e.g., without disturbing sleep) and can utilize a larger column.

[0313] In some implementations, 3D-printed lattice structures can be used as dampers to reduce vibration. Reduced vibration can help lower the overall noise level of the device. For example, 3D-printed rubber arranged in a lattice structure (e.g., in an open Kelvin unit mode) can be used to absorb and dissipate mechanical energy, thereby suppressing mechanical vibrations generated by an oxygen concentrator. The use of Kelvin unit lattice structures can have the advantage of storing energy by utilizing their elastic deformation and returning to their original shape quickly like a spring when the force is removed. Such designs can be customizable, where the 3D-printed structure can be formed around the pump and act both as a damper and as a structure to hold it in place, keeping the pump suspended, thereby further reducing vibration. In some implementations, the 3D-printed lattice structure can be configured to more efficiently direct cooling airflow to cool the pump.

[0314] In some embodiments, the disclosed oxygen concentrator may include a custom power supply unit that can be incorporated into the device, for example, by replacing the back cover.

[0315] In some embodiments, a replaceable module within the disclosed oxygen concentrator can be used to switch from continuous titration mode to automatic titration mode. For example, the replaceable module located below the cannula outlet port can be replaced by a "smart" module containing an oxygen sensor and a two-way valve to activate automatic titration and a replaceable filter. Such a module allows the device to switch from a continuous device to a pulse dosing device with the ability to detect respiration, adjust oxygen flow, and titrate.

[0316] Other embodiments will be apparent from the description and practice of the embodiments disclosed herein. The description and examples are intended to be illustrative only, and the true scope and spirit of the disclosed embodiments are indicated by the following claims.

Claims

1. A portable oxygen concentrator, the portable oxygen concentrator comprising: A first column and a second column, wherein the first column and the second column contain an adsorbent; One or more pumps; Product buffer; Multiple valves fluidly connected to the first column, the second column, the one or more pumps, and the product buffer; and The controller is configured to repeatedly cycle through the following phases: (a) The pressure in the first column is increased by connecting the first column to a positive pressure pump, and the concentrated oxygen in the first column is released to the product buffer. (b) The pressure in the first column and the second column is balanced by connecting the first column to the second column. (c) Reducing the pressure in the first column by connecting the first column to a negative pressure pump, and (d) Equalize the pressure in the first column and the second column by connecting the first column to the second column.

2. The portable oxygen concentrator of claim 1, wherein the controller is further configured to: reduce the pressure in the second column by connecting the second column to the negative pressure pump when the pressure in the first column is increased.

3. The portable oxygen concentrator of claim 1, wherein the controller is further configured to: when the pressure in the first column is reduced, increase the pressure in the second column by connecting the second column to the positive pressure pump, and release the concentrated oxygen to the product buffer.

4. The portable oxygen concentrator according to claim 1, further comprising: Pressure sensor; Flow sensor; Product purity sensor; and Processor, the processor being configured to execute stored instructions to: The system receives a set of user inputs through a user interface, including requirements for product purity, product flow rate, and concentrated oxygen output frequency. Receive measurement data from the pressure sensor, the flow sensor, and the product purity sensor; Combine the set of user inputs and the measurement data with the stored initialization characteristic data; as well as Determine the timing of the cyclic sequence for the first column and the second column respectively.

5. The portable oxygen concentrator of claim 4, wherein the processor is further configured to determine the remaining capacity of the first column and the second column.

6. The portable oxygen concentrator according to claim 4, wherein the stored initialization characteristic data includes pressure pump characteristics and vacuum pump characteristics.

7. The portable oxygen concentrator of claim 4, wherein the stored initialization characteristic data includes moisture contamination characteristics.

8. The portable oxygen concentrator of claim 4, further comprising an output component for displaying the estimated remaining capacity of the first column and the second column.

9. The portable oxygen concentrator of claim 8, wherein the output displays the user's health parameters and the measurement data.

10. The portable oxygen concentrator of claim 1, wherein the product buffer is housed in a removable module, the removable module further comprising a filter, an inflatable oxygen reservoir, and a check valve.

11. The portable oxygen concentrator of claim 1, wherein the product buffer is configured to be filled with an adsorbent to increase the storage capacity of the product buffer, improve the purity of the oxygen, or stabilize the flow rate of the concentrated oxygen.

12. The portable oxygen concentrator of claim 10, wherein the inflatable oxygen reservoir is an inflatable sac.

13. The portable oxygen concentrator of claim 10, wherein the inflatable oxygen reservoir is extendable from a single circular point on the flow path.

14. The portable oxygen concentrator of claim 10, wherein the check valve is a one-way duckbill valve configured to inflate the inflatable oxygen reservoir.

15. The portable oxygen generator of claim 10, wherein the check valve needs to be opened under pressure before allowing air to pass through the check valve.

16. The portable oxygen generator of claim 14, wherein the check valve is located at a distal point along the flow path without covering the filling hole of the inflatable oxygen reservoir.

17. The portable oxygen concentrator of claim 1, wherein the positive pressure pump and the negative pressure pump are located on a single dual-head pump.

18. A method for operating a portable oxygen concentrator, the method being performed by a controller, wherein the portable oxygen concentrator includes one or more pumps and a plurality of valves fluidly connected to a first column containing an adsorbent, a second column containing an adsorbent, and a product buffer, the method comprising repeatedly cycling the following stages: (a) The pressure in the first column is increased by connecting the first column to a positive pressure pump, and the concentrated oxygen in the first column is released to the product buffer. (b) The pressure in the first column and the second column is balanced by connecting the first column to the second column. (c) Reducing the pressure in the first column by connecting the first column to a negative pressure pump, and (d) Equalize the pressure in the first column and the second column by connecting the first column to the second column.

19. The method of operating a portable oxygen concentrator according to claim 18, wherein the controller is further configured to: reduce the pressure in the second column by connecting the second column to the negative pressure pump when the pressure in the first column is increased.

20. The method of operating a portable oxygen concentrator according to claim 18, wherein the controller is further configured to: when the pressure in the first column is reduced, increase the pressure in the second column by connecting the second column to the positive pressure pump, and release the concentrated oxygen to the product buffer.

21. The method of operating a portable oxygen concentrator according to claim 18, wherein when executed by at least one processor, the method provides operation comprising: The system receives a set of user inputs through a user interface, the set of user inputs including at least requirements for product purity, product flow rate, and concentrated oxygen output frequency; Measurement data is received from at least one of a pressure sensor, a flow sensor, and a product purity sensor; Combine the set of user inputs and the measurement data with the stored initialization characteristic data; as well as Determine the timing of the cyclic sequence for the first column and the second column respectively.

22. The method of operating a portable oxygen concentrator according to claim 21, the method further comprising determining the remaining capacity of the first column and the second column.

23. The method of operating a portable oxygen concentrator according to claim 21, wherein the stored initialization characteristic data includes pressure pump characteristics and vacuum pump characteristics.

24. The method of operating a portable oxygen concentrator according to claim 21, wherein the stored initialization characteristic data includes moisture contamination characteristics.

25. The method of operating a portable oxygen concentrator according to claim 21, the method further comprising an output component for displaying an estimated remaining capacity of the first column and the second column.

26. The method of operating a portable oxygen concentrator according to claim 25, wherein the output displays the user's health parameters and the measurement data.

27. The method of operating a portable oxygen concentrator according to claim 18, wherein the product buffer is housed in a removable module, the removable module further comprising a filter, an inflatable oxygen reservoir, and a check valve.

28. The method of operating a portable oxygen concentrator according to claim 18, wherein the product buffer is configured to be filled with an adsorbent to increase the storage capacity of the product buffer, improve the purity of the oxygen, or stabilize the flow rate of the concentrated oxygen.

29. The method of operating a portable oxygen concentrator according to claim 27, wherein the inflatable oxygen reservoir is an inflatable balloon.

30. The method of operating a portable oxygen concentrator according to claim 29, wherein the inflatable oxygen reservoir is capable of being extended from a single circular point on the flow path.

31. The method of operating a portable oxygen concentrator according to claim 27, wherein the check valve is a one-way duckbill valve configured to inflate the inflatable oxygen reservoir.

32. The method of operating a portable oxygen concentrator according to claim 27, wherein the check valve needs to be pressure-opened before allowing air to pass through the check valve.

33. The method of operating a portable oxygen concentrator according to claim 27, wherein the check valve is located at a distal point along the flow path without covering the filling hole of the inflatable oxygen reservoir.

34. The method for operating a portable oxygen concentrator according to claim 18, wherein the positive pressure pump and the negative pressure pump are on a single dual-head pump.

35. A portable oxygen concentrator, the portable oxygen concentrator comprising: A first column and a second column, wherein the first column and the second column contain an adsorbent; One or more pumps; Multiple valves fluidly connected to the first column, the second column, and the one or more pumps; and A removable module, the removable module comprising: Product buffers filled with adsorbent. Inflatable oxygen storage device, and A duckbill valve with an opening pressure is configured to inflate the inflatable oxygen reservoir.

36. The portable oxygen concentrator of claim 35, wherein the inflatable oxygen reservoir is an inflatable sac.

37. The portable oxygen concentrator of claim 36, wherein the inflatable oxygen reservoir is extendable from a single circular point on the flow path.

38. The portable oxygen generator of claim 35, wherein the check valve needs to be opened under pressure before allowing air to pass through the check valve.

39. The portable oxygen generator of claim 35, wherein the check valve is located at a distal point along the flow path without covering the filling hole of the inflatable oxygen reservoir.

40. The portable oxygen generator of claim 36, wherein the flow path has a reduced inner diameter around the opening of the inflatable oxygen reservoir.

41. The portable oxygen generator of claim 35, wherein the portable oxygen concentrator includes a pressure sensor adjacent to the removable module, and a high rate of pressure change detected by the pressure sensor indicates when the removable module should be replaced.

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